#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <cmath>

#define rep(x,to) for(int x=0;x<to;x++)
#define rep2(x,from,to) for(x=from;x<to;x++)

using namespace std;


int main(void){

double v,wn;
int n;

	while(cin >> v ){
		double h = 4.9 * (v / 9.8) * (v / 9.8);
		n = ceil(( h + 5 ) / 5);
//		n = (int)wn;
//		n = n + (wn==n? 0: 1);
		cout << n << endl;
	}
	
	return 0;
}