#include<iostream>
using namespace std;

int cont(float y)
{
    int cont = 1;
    while(y>0){	
	y -= 5;
	cont++;
    }
    return cont;
}

int main()
{
    float y, nv;
    while(cin >> nv)
    {
	y = (nv * nv) / 19.6;
	
	cout << cont(y) << endl;
    }
}