#include<bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n; // 输入整数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;
	}
}
/**************************************************************
	Problem: 1299
	User: zhengzihao
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/