#include <bits/stdc++.h>
#define INF 2000000000000000000
#define ll long long
using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll a, b, c, d, e, f;
  cin >> a >> b >> c >> d >> e >> f;
  long double ans = f - e + (c * c + d * d) / ((long double)4.0 * a);
  cout << pow(ans, 0.5) << "\n";
}