#include<iostream>
#include<algorithm>
#include<cctype>
#include<cstring>
#include<cstdlib>
#include<vector>
#include<string>
#include<cmath>
using namespace std;
#define REP(i, j) for(int i = 0; i < j; i++)
#define FOR(i, j, k) for(int i = j; i < k; i++)
const double EPS = 1e-8;
const int INF = 1e9;

int main(){
    double minv;
    while(cin >>minv){
        double t = minv / 9.8, y = 4.9 * t * t;
        cout <<(int)(y / 5) + ((y < 5.0 || abs((int)(y / 5) * 5 - y) < EPS)? 1 : 2) <<endl;
    }
    return 0;
}