Graph Algorithms · Hard problem

A weighted graph has vertices $p,q,r,s,t,u$ and edges $pq{:}4, pr{:}2, qr{:}1, qs{:}7, rs{:}3, rt{:}6, st{:}2, su{:}5, tu{:}4$. Dijkstra's algorithm from $p$ builds a shortest-path tree (each vertex is joined by the last edge of its shortest route from $p$). What is the total weight of that tree?