#include<iostream>
#include<iomanip>
#include<vector>
#include<queue>
#include<list>
#include<stack>
#include<algorithm>
#include<cmath>
#include<memory>

using namespace std;

int main()
{
  double v;

  while ( cin >> v )
    {
      cout << 1 + ceil( v * v / 98.0 ) << endl;
    }
  
  return 0;
}