#include <iostream>
using namespace std;
int main() {
	double v;
	while(cin >> v && v){
		double t;
		int h;
		t = v/9.8;
		for(int i=0; ; ++i){
			if(4.9*t*t <= 5*i-5){
				h = i;
				break;
			}
		}
		cout << h << endl;
	}
}