B"You are given a simple undirected graph, consisting of n vertices and m edges. The vertices are numbered from 1 to n . The i -th vertex has a value a_i written on it. You will be removing vertices from that graph. You are allowed to remove vertex i only if its degree is equal to a_i . When a vertex is removed, all edges incident to it are also removed, thus, decreasing the degree of adjacent non-removed vertices. A valid sequence of removals is a permutation p_1, p_2, ... , p_n (1 <= p_i <= n) such that the i -th vertex to be removed is p_i , and every removal is allowed. A pair (x, y) of vertices is nice if there exist two valid sequences of removals such that x is removed before y in one of them and y is removed before x in the other one. Count the number of nice pairs (x, y) such that x < y . The first line contains a single integer t ( 1 <= t <= 10^4 ) -- the number of testcases. The first line of each testcase contains two integers n and m ( 1 <= n <= 10^5 ; 0 <= m <= min(10^5, frac{n cdot (n - 1)}{2}) ) -- the number of vertices and the number of edges of the graph. The second line contains n integers a_1, a_2, ... , a_n ( 0 <= a_i <= n - 1 ) -- the degree requirements for each removal. Each of the next m lines contains two integers v and u ( 1 <= v, u <= n ; v neq u ) -- the description of an edge. The graph doesn't contain any self-loops or multiple edges. The sum of n over all testcases doesn't exceed 10^5 . The sum of m over all testcases doesn't exceed 10^5 . Additional constraint on the input: there always exists at least one valid sequence of removals. For each testcase, print a single integer -- the number of nice pairs of vertices. "...