#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(nullptr);
	ll N;
	cin >> N;
	ll ok = 1, ng = 1e9 + 12;
	while(ng - ok > 1) {
		ll mi = (ok + ng) >> 1;
		if(mi * mi <= N) ok = mi;
		else ng = mi;
	}
	cout << ok << "\n";
}