#include<iostream>
#include<conio.h>
void main()
{
  int n,i,flag=0;
  cout<<"Enter a positive integer: ";
  cin>>n; 

  for(i=2;i<=n/2;++i)
  {
      if(n%i==0)
      {
          flag=1;
          break;
      }
  } 

  if(flag==0)

   { 
      cout<<"This is a prime number"; 

   }

 else
   {

       cout<<"This is not a prime number"; 

   }

 getch(); 

 }

Enter a positive integer: 29
This is a prime number.