C :

#include<stdio.h>
int main()
{
    int n,i,k;
    while(scanf("%d",&n)!=EOF)
    {    if(n==1) printf("not prime\n");

      else  for(i=2;i<=n;i++)
        if(n%i==0) break;
        if(i>n-1)
            printf("prime\n");

        else printf("not prime\n");
    } return 0;

}

C++ :

#include<cstdio>
#include<cmath>

int n;

int main()
{
    while(scanf("%d",&n) != EOF)
    {
        bool flag = true;
        if(n < 2)
            printf("prime\n");
        else
        {
            for(int i = 2;i <= sqrt(n);i++)
            {
                if(!(n % i))
                {
                    flag = false;
                    break;
                }
            }
            if(flag)
                printf("prime\n");
            else
                printf("not prime\n");
        }
    }
    return 0;
}