По заданым значениям х и у найти значение величины log x y (log с основанием х)

#include <iostream>
#include <cmath>
#define _USE_MATH_DEFINES
using namespace std;
 
int main ()
{
    double x=0,y=0,a=0;
    cout<<"This programm calculates the logarithm of y to base x."<<endl;
    cout<<"Please input x and press Enter.It must be integer."<<endl;
    cin>>x;
    cout<<"Please input y and press Enter.It must be integer."<<endl;
    cin>>y;
    a=log(y)/log(x);
        if(x<0) cout<<"Error."<<endl;
    else  if(x==1) cout<<"Error."<<endl;
          else if(y<0) cout<<"Error."<<endl; 
          else cout<<"Result:"<<a<<endl;
    system ("pause");
        return 0;
}

 double x=0,y=0,a=0;
 cout<<"This programm calculates the logarithm of y to base x."<<endl;
 cout<<"Please input x and press Enter.It must be integer."<<endl;
 cin>>x;
 cout<<"Please input y and press Enter.It must be integer."<<endl;
 cin>>y;
 if(x<=0) cout<<"Error."<<endl;
 else if(x==1) cout<<"Error."<<endl;
 else if(y<=0) cout<<"Error."<<endl; 
 else cout<<"Result:"<<log(y)/log(x)<<endl;