/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.08.21 22:04:55
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int a,b,c,d,e,f;cin >> a >> b >> c >> d >> e >> f;
    printf("%.10f\n",sqrt((4.0 * a * (f - e) + c * c + d * d) / (4 * a * a)));
    return 0;
}