#include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
#include <cmath>
using namespace std;

int main(){
	int n;
	while(cin >> n){
		n = n*n/19.6;
		n = (n+5)/5;
		cout << n <<"\n";
	}
	return 0;
}