#include <cmath>
#include <cstdio>
#include <iostream>

using namespace std;

int main() {
	float v;
	while (scanf("%f", &v) != EOF) {
		printf ("%d\n", (int)ceil((v * v / 19.6 + 5) / 5.0 + 0.000000001));
	}
	return 0;
}