#include <iostream>
#include <cmath>
using namespace std;

int main() {
  double v;
  while(cin >> v) {
    double N = v*v/98.0+1;
    if(N != (int)N) ++N;
    cout << (int)N << endl;
    //cout << (int)ceil(v*v/98.0+1) << endl;
  }
  return 0;
}