#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<n;i++)
#define int long long

signed main(){
  double a,b,c,d,e,f,x,y,r;
  cin>>a>>b>>c>>d>>e>>f;
  x=c/a/2;
  y=d/a/2;
  r=f/a-e/a+x*x+y*y;
  cout<<pow(r,0.5)<<endl;
  return 0;
}