#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<<endl;	
	}
}
/**************************************************************
	Problem: 1299
	User: huanglingkai
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/