#include <bits/stdc++.h>

using namespace std;

int main(void) {
  double v;
  while (cin >> v) {
    int n = 0;
    while (n - v * v / (19.6 * 5) - 1.0 < -1e-10) {
      n++;
    }
    cout << n << endl;
  }

  return 0;
}
