Radius, diameter and center of graph 
The eccentricity $ecc(v)$ of $v$ in $G$ is the greatest distance from $v$ to any other node.
The radius $rad(G)$ of $G$ is the value of the smallest eccentricity.
The diameter $diam(G)$ of $G$ is the value of the greatest eccentricity.
The center of $G$ is the set of nodes $v$ such that $ecc(v) = rad(G)$

Find the radius, diameter and center of the graph

Appreciate as much help as possible.
I tried following an example and still didn't get it, when you count the distance from a node to another, do you count the starting node too or you count the ending node instead. And when you count, do you count the ones above and below or how do you count? :)

to find  the  radius of  aconnected  graph  G 
 denoted by r=[v+e]÷[e-2]
       where v=vertex of the graph
                  e=edge of the graph 
