The total irregularity of a graph

In this note a new measure of irregularity of a simple undirected graph $G$ is introduced. It is named the total irregularity of a graph and is defined as ${\text{irr}}_t(G)=1\mathrm{/}2{\sum }_{u,v\in V(G)}\mathrm{\mid }{d}_G(u)-d_G(v)\mathrm{\mid }$, where $d_G(u)$ denotes the degree of a vertex $u\in V(G)$. The graphs with maximal total irregularity are determined. It is also shown that among all trees of same order the star graph has the maximal total irregularity.