#include <bits/stdc++.h>

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  long long N; std::cin >> N;
  long long ok = 0, ng = 2e9;
  while (ng - ok > 1) {
    long long mid = (ok + ng) / 2;
    if (mid * mid > N) {
      ng = mid;
    } else {
      ok = mid;
    }
  }
  std::cout << ok << '\n';
}