#include <iostream>
#include <iomanip>
#include <list>
#include <map>
#include <algorithm>
#include <stack>
#include <string>
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>

using namespace std;

int main(){
	double t,v,y,n;
	while(cin >> v){
		n = 1;
		t = v / 9.8;
		y = 4.9 * t * t;

		while(1){
			if(y < 5 * n - 5){
				break;
			}
			else{
				n++;
			}
		}

		cout << n << endl;
	}

	return 0;
}