#include <cmath>
#include <iostream>
#include <string>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <sstream>
#include <vector>
#define P(a) ((a)*(a))
using namespace std;

int main(){
    double t,y,v;
    int f;
    while(cin >> v){
        t=v/9.8;
        y=4.9*t*t;
        f=ceil((y+5.0)/5.0);
        cout << f << endl;
    }
    return 0;
}