#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	cin>>a;
	if(a%2==0)
		cout<<2<<endl;
	if(a%3==0)
		cout<<3<<endl;
	if(a%5==0)
		cout<<5<<endl;
	if(a%7==0)
		cout<<7<<endl;
	return 0;
}

/**************************************************************
	Problem: 1299
	User: panyuchen
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/