#include <iostream>
using namespace std;
int LeastHeight(int v) {
  double y, t;
  int N;
  t = v / 9.8;
  y = 4.9 * t * t;
  N = int((y + 5) / 5 + 1);
  return N;
}
int main() {
  double v;
  while(cin >> v) {
	cout << LeastHeight(v) << endl;
  }

  return 0;
}