#include <iostream>
using namespace std;

int main() {
    int x;
    cin >> x;

    bool flag = true;
    for(int i = 2; i <= x / 2; ++i)
    {
        if(x % i == 0)
        {
            cout << "不是质数";
            flag = false;
            break;
        }
    }

    if(flag)
    {
        cout << "是质数";
    }
}