#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) for (int i = 0; i < (n); i++)
#define RREP(i, n) for (int i = (n) - 1; i >= 0; i--)
#define sz(obj) ((int)(obj).size())
#define pf push_front
#define pb push_back

int main()
{
  double v, y, floor;

  while (cin >> v){
    int t = 1;
    while (9.8 * t < v) t++;
    y = 4.9 * t * t;
    floor = (y - 5) / 5;
    if (v == 0) floor = 0;
    if (v <= 9) floor = 1;
    printf("%d\n", (int)floor + 1);
  }
}