#include <bits/stdc++.h>
using namespace std;

using Int = long long;
const char newl = '\n';

template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
template<typename T> void drop(const T &x){cout<<x<<endl;exit(0);}
template<typename T=int>
vector<T> read(size_t n){
  vector<T> ts(n);
  for(size_t i=0;i<n;i++) cin>>ts[i];
  return ts;
}


struct Precision{
  Precision(){
    cout<<fixed<<setprecision(12);
  }
}precision_beet;

//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);
  using D = long double;

  D a,b,c,d,e,f;
  cin>>a>>b>>c>>d>>e>>f;

  assert(abs(a)==abs(b));

  b/=a;
  c/=a;
  d/=a;
  e/=a;
  f/=a;
  a/=a;

  drop(sqrt(f-e+(c/2)*(c/2)+(d/2)*(d/2)));
  return 0;
}