AOJ Volume0-0024

http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0024&lang=jp

#define _USE_MATH_DEFINES
#include <iostream>
#include <vector>
#include <list>
#include <cmath>
using namespace std;

int main ()
{
    double N = 0;
    while (cin >> N) {
        int i = 1;
        while (1) {
            double hoge = 5 * i - 5;
            double v = 9.8 * sqrt(hoge / 4.9);
            if (v > N) {
                break;
            }
            i++;
        }
        cout << i << endl;
    }
        
    return 0;
}