#include <bits/stdc++.h>

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  const long double eps = 1e-6;
  int c;
  std::cin >> c;
  auto f = [&](long double x) -> long double {
    return x * x * x * x * x + x - c;
  };
  long double l = 0, r = 100;
  while (r - l > eps) {
    long double mid = (r + l) / 2;
    (f(mid) < 0 ? l : r) = mid;
  }
  std::string ans = std::to_string(l);
  std::cout << ans.substr(0, 5) << '\n';
}