#include <iostream>
using namespace std;
int main()
{
    double v;
    while(cin >> v,v)
    {
        double t = 0,y = 0;
        t = v/9.8;
        y = 4.9*t*t;

        double f = 0;
        y = y-5;
        f = y/5;
        cout << f+1 << endl;
    }
}