GATE Computer Science (CS) 2014 Shift 1 Solved Paper

Consider an undirected graph G where self-loops are not allowed. The vertex set of G is {(i, j): 1 ≤ i ≤ 12, 1 ≤ j ≤ 12}. There is an edge between (a, b) and (c, d) if |a − c| ≤ 1 and |b − d| ≤ 1.
The number of edges in this graph is __________.