
var input = "";
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function(chunk){input += chunk});
process.stdin.on('end', function()
{
  input = input.split('\n');
  for(var i in input)
  {
    console.log(Math.ceil(Math.pow(input[i] / 9.8, 2)  * 4.9 / 5) + 1);
  }
});