Правильный ли код?

#include <vcl.h>
#pragma hdrstop
 
#include "main.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
#include <iostream> //дериктива для использования cout, cin
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
int main()
{
int n = 0;
 
  std::cout << "n = ";
  std::cin >> n;
 
  int m = 0;
 
  std::cout << "m = ";
  std::cin >> m;
 
  while(m <= n){
    std::cout << "m must be > than n." 
              << "m = ";
    std::cin >> m;
  }
 
  int sum = 0;
 
  for(int i = n; i <= m; ++i)
    sum += i;
 
  std::cout << "sum = ";
  std::cout << sum;
 
  std::cout << std::endl;
 
  system("pause");
 
  return 0; //возращения 0 функции "мэйн"
}

#include <iostream.h>
#include <stdlib.h>
 
int main()
{
int n = 0;
 
cout << "n = ";
cin >> n;
 
int m = 0;
 
cout << "m = ";
cin >> m;
 
while(m <= n){
cout << "m must be > than n." 
<< "m = ";
cin >> m;
}
 
int sum = 0;
 
for(int i = n; i <= m; ++i)
sum += i;
 
cout << "sum = ";
cout << sum;
 
cout << endl;
 
system("pause");
 
return 0; 
}

#include <iostream.h>
#include <stdlib.h>
 
int main()
{
int n = 0;
int m = 0;
cout << "n = ";
cin>>n;
cout << "m = ";
cin>>m;
int sum = 0;
for(int i = n; i<m; ++i)
sum += i;
cout << "sum = ";
cout << sum<<'\n';
 
return 0; 
}

#include <iostream.h>
#include <stdlib.h>
 
int main()
{
int n = 0;
int m = 0;
cout << "n = ";
cin>>n;
cout << "m = ";
cin>>m;
int sum = 0;
for(int i = n; i<m; ++i)
sum += i;
cout << "sum = ";
cout << sum<<'\n';
 
return 0; 
}