#include <bits/stdc++.h>
using namespace std;
using ld = long double;
const ld eps = 1e-8;

int main()
{
	ld v;
	while (cin >> v) {
		cout << ((int)floor(v * v / 19.6 - eps) + 4) / 5 + 1 << endl;
	}
	return 0;
}