#include <iostream>
using namespace std;
 
int main() {
    int n;
    cin >> n;
 
    if (n % 2 == 0) {
        cout << 2 << endl;
    }
    if (n % 3 == 0) {
        cout << 3 << endl;
    }
    if (n % 5 == 0) {
        cout << 5 << endl;
    }
    if (n % 7 == 0) {
        cout << 7 << endl;
    }
 
    return 0;
}    
/**************************************************************
	Problem: 1299
	User: baizhoudeyueguang
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/