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

int main()
{
    int y, t, v, nv, cont = 1;
    while(cin >> nv)
    {
	y = (nv * nv) / 19.6;
	
	while(y>0){	
	    y -= 5;
	    cont++;
	}
	
	cout << cont << endl;
    }
}