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