#include <iostream>

using namespace std;

int main()
{
	double v, y, t;
	int floor;

	while (cin >> v)
	{
		if(cin.eof())    break;

		t = v / 9.8;
		y = 4.9 * t * t;
	
		floor = int(y/5 + 0.9999999999)+1;

		cout << floor << endl;
	}

	return 0;
}