#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: wqc123
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/