190B - Surrounded - CodeForces Solution

#include<bits/stdc++.h>
 
using namespace std;
 
int a,b,r,q,w,e;
double d,h;
 
int main()
{
cin>>a>>b>>r;
cin>>q>>w>>e;
d=sqrt((q-a)*(q-a)+(w-b)*(w-b));
if(d>e+r)h=d-r-e;
else if(d<abs(r-e))h=abs(r-e)-d;
cout<<fixed<<setprecision(15)<<h/2<<"\n";
}