#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: fuyijun
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/