'use strict';

var input = require('fs').readFileSync('/dev/stdin', 'utf8');
var minvs = input.trim().split('\n');
var minv;
while (minv = minvs.shift()) {
	var t = minv / 9.8;
	var y = 4.9 * t * t;
	var f = Math.ceil((y + 5)/5);
	console.log(f);
}