#include <bits/stdc++.h>

#include <atcoder/modint>
using namespace std;
using mint = atcoder::modint1000000007;
void fast_io() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
}
int main() {
    fast_io();
    int a, b, c, d, e, f;
    cin >> a >> b >> c >> d >> e >> f;
    double ans = (double)(4 * a * (f - e) + c * c + d * d) / (4 * a * a);
    ans = sqrt(ans);
    cout << setprecision(16) << fixed << ans << endl;
}