#include<iostream>
using namespace std;

int main()
{
	double _t, t, y, N;
	while (cin >> _t){
		t = _t / 9.8;
		y = 4.9 * t * t;
		N = (y + 5) / 5;

		cout << static_cast<int>(N+1) << endl;
	}
	return 0;
}