//#define _USE_MATH_DEFINES
#include <cmath>
#include <iostream>
//#include <stdio.h>
//#include <stdlib.h>
//#include <iomanip>
#include <vector>
//#include <string>
//#include <algorithm>
//#include <functional>
//#include <time.h>
//#include <sstream>
//#include <queue>

using namespace std;


int main(){

	const int H = 5;
	double v, t, y;
	int ans;

	while (cin >> v){
		if (v == 0) ans = 1;
		else{
			t = v / 9.8;
			y = 4.9 * t * t;
			ans = (int)((y + 10 + 1) / H);
		}
		cout << ans << endl;
	}


	return 0;
}