#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: zhengzihao3
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/