Using Bellman$-$Ford, find the shortest path tree from the node $3$

the shortest$-$path tree consists of edges

the number of iterations of BF is

renumber the nodes such that after renumbering BF needs only $2$ iterations to find shortest path tree old number $1,2,3,4,5,6$

new number $-$ the maximum number of iterations over all possible renumberings is $?$