program bilangan. primaa c++

#include <iostream>
#include <conio.h>
#include <string>
#include <cstdlib>

using namespace std;

//nt main(int argc, char *argv[])
int main()
{
     int x,a,b;
     char i;
     {
          b=1;
         // i1:clrscr();
         cout<<"PROGRAM UNTUK MEMERIKSA BILANGAN PRIMA"<<endl<<endl;
          cout<<"Masukkan Bilangan Untuk di Cek: ";
          cin>>x;
          //cout<<endl;
          for(a=2;a<=x-1;a++)
          {
          if(x%a==0)
          {
                        b=0;
                        break;
                        }
                        }
                        if (b==1)
                        {
                        cout<<x<<"merupakan bilangan prima";
                         }
                         else
                          {
                           cout<<x<<"bukan bilangan prima";
                           }
                            if(b==0)
                            cout<<endl;
                            cout<<endl;
                            cout<<endl;
                            cout<<"ulangi (y/n) ?";
                            cin>>i;
                            if(i=='y'){}
                           // goto i1,
                            else
                            cout<<"terima kasih";
                           
                            }
    system("PAUSE");
    return EXIT_SUCCESS;
}