#include <iostream>
using namespace std;

#define EPS (1e-6)

int main(){
	double min_v, n;
	int i;
	while(cin >> min_v){
		n = min_v * min_v / 98.0 + 1.0;
		i = 1;
		while(n - (double)i > EPS){
			i++;
		}
		cout << i << endl;
	}
	return 0;
}