#include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
using namespace std;

#define rep(i,n) for(int i=0;i<int(n);++i)


double v,y,t;
int n;


int main(){
	
	
	while(cin>>v){
		t = v/9.8;
		y = 4.9*t*t;
		rep(i,1000000){
			if(5*i-5>=y){
				n = i;
				break;
			}
		}
		cout<<n<<endl;
	}
	return 0;
}