Что за ошибка: "E2015 Ambiguity between 'time' and 'std::time"?

# include <iostream.h>
# include <conio.h>
# include <string.h>
# include <math.h>
 
class time
 {
  protected:  
    int hr, min;  
  public:
    time ()  
     {
      hr=min=0;
     }
    time (int h, int m) 
     {
      hr=h;
      min=m;
      cout<<"\nTime is set to specified value.\n";
     }
    void display() 
     {
      while (min>59)
       {
         min-=59;
         hr++;
       }
 
      while (hr>23)
       {
        hr-=24;
       }
      if (hr<0) hr+=24;
      cout<<"\nTime set is: "<<(hr<10?"0":"")<<hr<<(min<10?":0":":")<<min;
      char p[2];
      int h=hr;
       if ((h>=0)&&(h<=12)) strcpy(p,"am");
       else {h-=12; strcpy(p,"pm");}
      cout<<"\nTime set is: "<<(h<10?"0":"")<<h<<(min<10?":0":":")<<min<<" "<<p;
     }
    int mincount ()  
     {int m;
      m=min+60*hr;
      return m;
     }
    time operator ++() 
     {
       hr++;
       return *this;
     }
    time operator --(int) 
     {
       hr--;
       return *this;
     }
     ~time()  
     {cout<<"\nRobota clasy time zakinchena.";
     }
 };
 
class local_time : public time  
 {
  protected:
    int t_zone;
    char city[30];
  public:
    local_time():time()  
     {
      t_zone=2;
      strcpy(city,"Kiev");
     }
    local_time(int h, int m, int zone, char c[30]): time (h,m) 
     {                                  
      t_zone=zone;
      strcpy(city,c);
     }
 
    int operator - (local_time&t) 
     {              
      int tmp;
      tmp = this->t_zone-t.t_zone;
      return abs(tmp);
     }
    void display() 
     {
      time :: display();
      cout<<"\nTime zone is GMT"<<(t_zone>0?"+":"")<<t_zone;
      cout<<"\nCity set is "<<city;
     }
    ~local_time() 
    {cout<<"\nRobota clasy miscevuy chas zakinchena.";
    }
 };
 
  void chosecity (int t) 
      {cout<<"Mojluvi mista:   ";           
       switch (t)
      {case 0: {cout<<"London, Lisbon"; break;}
       case 1: {cout<<"Paris, Berlin, Rome, Warsaw, Budapest, Praha"; break;}
       case 2: {cout<<"Kyiv, Helsinki, Istambul, Athens";break;}
       case 3: {cout<<"Moscow, Jeddah, Nairobi";break;}
       case 4: {cout<<"Abu Dabi";break;
       case 5: {cout<<"Islamabad, Tashkent"; break;}
       case 6: {cout<<"Dhaka";break;}
       case 7: {cout<<"Bangkok, Jakarta, Hanoi"; break;}
       case 8: {cout<<"Hong Kong, Beijing"; break;}
       case 9: {cout<<"Tokyo, Seul"; break;}
       case 10: {cout<<"Sydney, Guam";  break;}
       case 11: {cout<<"Magadan"; break;}
       case 12: {cout<<"Wellington, Auckland";break;}
       case -11: {cout<<"Midway, Samoa"; break;}
       case -10: {cout<<"Hawaii, Honolulu";break;}
       case -9: {cout<<"Alaska"; break;}
       case -8: {cout<<"LA, San Francisco"; break;}
       case -7: {cout<<"Denver, Phoenix";break;}
       case -6: {cout<<"Chicago, Dallas"; break;}
       case -5: {cout<<"New York, Washigton DC";break;}
       case -4: {cout<<"Caracas, La Paz"; break;}
       case -3: {cout<<"Brasilia, Buenos Aires";break;}
       case -2: {cout<<"Mid-Atlantic"; break;}
       case -1: cout<<"Azores";
      } }
 
      }
void main ()  
 {
  int g, mi;
  cout<<"Vvedit hodynu\n";
  cin>>g;
  cout<<"Vvedit hvylynu\n";
  cin>>mi;
  time a(g,mi);
  time b;
  cout<<"\nVuvedennia konstruktora dovilnoho pokaznuka chasy\n";
  a.display();
  getch();
  cout<<"\nVuvedennia konstruktora za zamovchyvanniam\n";
  b.display();
  getch();
  ++a;
  cout<<"\nPerevid godunnuka na 1 goduny vpered\n";
  a.display();
  getch();
  cout<<"\nPerevid godunnuka na 1 goduny nazad\n";
  b--;
  b.display();
  getch();
  cout<<"\nKilkist xvulun y  ";
  a.display();
  cout<<"\n="<<a.mincount();
  cout<<"\nVuvedennia dunamichnux danux\n";
  time *d =new time(12,3);
  d->display();
    int z;
    char misto[30];
  local_time c2;
  cout<<"\nVukorustannia klasy-nashadka:\n";
  cout<<"\nVvedit hodynu\n";
  cin>>g;
  cout<<"Vvedit hvylynu\n";
  cin>>mi;
  cout<<"\nVvedit nomer chasovoho poasu\n";
  cin>>z;
  chosecity(z);
  cout<<"\nVvedit nazvu mista \n";
  cin.get();
  cin.getline(misto,30);
 local_time c1(g,mi,z,misto);
 cout<<"\nVukluk konstruktora dovilnoho pokaznuka chasy\n";
  c1.display();
  getch();
  cout<<"\nVuvedennia konstruktora za zamovchyvanniam\n";
  c2.display();
  int r=c1-c2;
  cout<<"\nRiznuca y chasovux poiasax "<<r<<" hodun";
  if (r==1) cout<<"a";
  if ((r==2)||(r==3)||(r==4)) cout<<"u";
  delete d;
  getch();
 }

//
//  main.cpp
//  For Forum
//
//  Created by Александр Мещеряков on 08.12.15.
//  CEO/CIO
//  Copyright (c) 2015 Ltd. FTC Vertical. All rights reserved.
//
 
# include <iostream>
# include <string>
# include <math.h>
 
using namespace std;
 
class user_time
{
protected:
    int hr, min;
public:
    user_time ()
    {
        hr=min=0;
    }
    user_time (int h, int m)
    {
        hr=h;
        min=m;
        cout<<"\nTime is set to specified value.\n";
    }
    void display()
    {
        while (min>59)
        {
            min-=59;
            hr++;
        }
        
        while (hr>23)
        {
            hr-=24;
        }
        if (hr<0) hr+=24;
        cout<<"\nTime set is: "<<(hr<10?"0":"")<<hr<<(min<10?":0":":")<<min;
        char p[2];
        int h=hr;
        if ((h>=0)&&(h<=12)) strcpy(p,"am");
        else {h-=12; strcpy(p,"pm");}
        cout<<"\nTime set is: "<<(h<10?"0":"")<<h<<(min<10?":0":":")<<min<<" "<<p;
    }
    int mincount ()
    {int m;
        m=min+60*hr;
        return m;
    }
    user_time operator ++()
    {
        hr++;
        return *this;
    }
    user_time operator --(int)
    {
        hr--;
        return *this;
    }
    ~user_time()
    {cout<<"\nRobota clasy time zakinchena.";
    }
};
 
class local_time : public user_time
{
protected:
    int t_zone;
    char city[30];
public:
    local_time():user_time()
    {
        t_zone=2;
        strcpy(city,"Kiev");
    }
    local_time(int h, int m, int zone, char c[30]): user_time (h,m)
    {
        t_zone=zone;
        strcpy(city,c);
    }
    
    int operator - (local_time&t)
    {
        int tmp;
        tmp = this->t_zone-t.t_zone;
        return abs(tmp);
    }
    void display()
    {
        user_time :: display();
        cout<<"\nTime zone is GMT"<<(t_zone>0?"+":"")<<t_zone;
        cout<<"\nCity set is "<<city;
    }
    ~local_time()
    {cout<<"\nRobota clasy miscevuy chas zakinchena.";
    }
};
 
void chosecity (int t)
{cout<<"Mojluvi mista:   ";
    switch (t)
    {case 0: {cout<<"London, Lisbon"; break;}
        case 1: {cout<<"Paris, Berlin, Rome, Warsaw, Budapest, Praha"; break;}
        case 2: {cout<<"Kyiv, Helsinki, Istambul, Athens";break;}
        case 3: {cout<<"Moscow, Jeddah, Nairobi";break;}
        case 4: {cout<<"Abu Dabi";break;
            case 5: {cout<<"Islamabad, Tashkent"; break;}
            case 6: {cout<<"Dhaka";break;}
            case 7: {cout<<"Bangkok, Jakarta, Hanoi"; break;}
            case 8: {cout<<"Hong Kong, Beijing"; break;}
            case 9: {cout<<"Tokyo, Seul"; break;}
            case 10: {cout<<"Sydney, Guam";  break;}
            case 11: {cout<<"Magadan"; break;}
            case 12: {cout<<"Wellington, Auckland";break;}
            case -11: {cout<<"Midway, Samoa"; break;}
            case -10: {cout<<"Hawaii, Honolulu";break;}
            case -9: {cout<<"Alaska"; break;}
            case -8: {cout<<"LA, San Francisco"; break;}
            case -7: {cout<<"Denver, Phoenix";break;}
            case -6: {cout<<"Chicago, Dallas"; break;}
            case -5: {cout<<"New York, Washigton DC";break;}
            case -4: {cout<<"Caracas, La Paz"; break;}
            case -3: {cout<<"Brasilia, Buenos Aires";break;}
            case -2: {cout<<"Mid-Atlantic"; break;}
            case -1: cout<<"Azores";
        } }
    
}
int main ()
{
    int g, mi;
    cout<<"Vvedit hodynu\n";
    cin>>g;
    cout<<"Vvedit hvylynu\n";
    cin>>mi;
    user_time a(g,mi);
    user_time b;
    cout<<"\nVuvedennia konstruktora dovilnoho pokaznuka chasy\n";
    a.display();
//  gtch();
    cout<<"\nVuvedennia konstruktora za zamovchyvanniam\n";
    b.display();
//  getch();
    ++a;
    cout<<"\nPerevid godunnuka na 1 goduny vpered\n";
    a.display();
//  getch();
    cout<<"\nPerevid godunnuka na 1 goduny nazad\n";
    b--;
    b.display();
//  getch();
    cout<<"\nKilkist xvulun y  ";
    a.display();
    cout<<"\n="<<a.mincount();
    cout<<"\nVuvedennia dunamichnux danux\n";
    user_time *d =new user_time(12,3);
    d->display();
    int z;
    char misto[30];
    local_time c2;
    cout<<"\nVukorustannia klasy-nashadka:\n";
    cout<<"\nVvedit hodynu\n";
    cin>>g;
    cout<<"Vvedit hvylynu\n";
    cin>>mi;
    cout<<"\nVvedit nomer chasovoho poasu\n";
    cin>>z;
    chosecity(z);
    cout<<"\nVvedit nazvu mista \n";
    cin.get();
    cin.getline(misto,30);
    local_time c1(g,mi,z,misto);
    cout<<"\nVukluk konstruktora dovilnoho pokaznuka chasy\n";
    c1.display();
//  getch();
    cout<<"\nVuvedennia konstruktora za zamovchyvanniam\n";
    c2.display();
    int r=c1-c2;
    cout<<"\nRiznuca y chasovux poiasax "<<r<<" hodun";
    if (r==1) cout<<"a";
    if ((r==2)||(r==3)||(r==4)) cout<<"u";
    delete d;
//  getch();
}