#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)

typedef long long ll;

int main()
{
	ll N; cin >> N;
	rep(i, 2, sqrt(N)+1)
	{
		if (N % (ll)i == 0)
		{
			if(i == 2)
				cout << N/(ll)2 << endl;
			else
				cout << i << endl;
			return 0;
		}
	}
	cout << N << endl;
}