#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;
    }
}



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