// 2014/06/09 Tazoe

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	while(true){
		double v;
		cin >> v;

		if(cin.eof())
			break;

		int N = ceil(v*v/98.0)+1;

		cout << N << endl;
	}

	return 0;
}