#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int a, b, c, d, e, f;
  cin >> a >> b >> c >> d >> e >> f;
  long double ans = f - e + (a * c * c) / 4.0 + (b * d * d) / 4.0;
  cout << fixed << setprecision(15) << sqrtl(ans) << '\n';
  return 0;
}