#include <iostream>
#include <vector>

using namespace std;

int main(int argc, char *argv[]) {
  vector<int> result;
  double v, t, h;

  while (cin >> v) {
    t = v / 9.8;
    h = 4.9 * t * t;
    int n = 1;
    while (true)
      if (5 * (n - 1) >= h) {
        result.push_back(n);
        break;
      } else {
        n++;
      }
  }

  for (int i = 0; i < result.size(); i++)
    cout << result[i] << endl;
  return 0;
}