#include <iostream>

using namespace std;

int main()
{
    double v,y,t;
    int n;
    while(cin >> v)
    {
        t = v / 9.8;
        y = 4.9 * t * t;
        double n1 = (y + 5)/5;
        n = (n1 + 0.5);
        cout << n << endl;
    }
    return 0;
}