#include <iostream>
#include <stdio.h>
#include<math.h>
using namespace std;
int main()
{
	double n, a, b, r, s=0;
	cin >> n >> a >> b >> r;
	for (int i = 0;i < n;i++)
		s += 1.5 * r + 2 * sqrt(a * a + b * b) / 50;
	cout << (int)ceil(s);
}