#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;
	}
	return 0;
}

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