#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: lzc
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/