#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    double v;
    while(cin>>v) {
        double y=v*v/19.6;
        cout<<(int)ceil(y/5+1)<<'\n';
    }
    return 0;
}