#include<bits/stdc++.h>
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;
	
}

/**************************************************************
	Problem: 1299
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/