#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include<iomanip>
#include<cmath>
using namespace std;
using i32 = int_fast32_t;
using i64 = int_fast64_t;
#define rep(i, n) for (i32 i = 0; i < (i32)(n); i++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
using P = pair<i64,i64>;

int main(){
ios::sync_with_stdio(false);
std::cin.tie(nullptr);
i32 a,b,c,d,e,f;
cin >> a >> b >> c >> d >> e >> f;
i32 top = 4 * a * (f - e) + c * c + d * d;
i32 bottom = 4 * a * a;
cout << setprecision(10) << sqrtl(top / bottom) << endl;
}