#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for(int i = 0, i_length = (n); i < i_length; i++)
#define MOD 1000000007
#define ll long long

int main() {
	ll n;
	cin >> n;
	if (n == 1) {
		cout << 2 << endl;
		return 0;
	}
	if (n == 2) {
		cout << 3 << endl;
		return 0;
	}
	if (n == 3) {
		cout << 2 << endl;
		return 0;
	}
	for (int p = 2; p <= sqrt(n); p++)
	{
		ll t = 1;
		do
		{
			if (n % t == 0 && n / t <= p) {
				cout << p << endl;
				return 0;
			}
			t *= p;
			t++;
		} while (t <= n);
	}

	ll ans = 1000000000000;
	for (ll i = 1; i * i <= n; i++)
	{
		if (n % i == 0) {
			ll p = n / i - 1;
			if (i <= p) ans = min(ans, p);

			if (n / i != i) {
				ll p = i - 1;
				if (n / i <= p) ans = min(ans, p);
			}
		}
	}
	cout << ans << endl;
	return 0;
}