#include <iostream>
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: xiaomingze
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/