#include<iostream>
using namespace std;
int main(){
  double v,y,t,H,b;
  int h,a;
  while(cin>>v){
  t = v / 9.8;
  y = 4.9 * t * t;
  h = (y+5)/5;
  H = (y+5)/5;
  b = H - h; 
    if(b!=0) h = h + 1;
  cout << h << endl;
  }
  return 0;
}