from collections import defaultdict
 
def dfs(node, parent, graph, weights, subtree_sum):
    subtree_sum[node] = weights[node]
    for neighbor in graph[node]:
        if neighbor != parent:
            subtree_sum[node] += dfs(neighbor, node, graph, weights, subtree_sum)
    return subtree_sum[node]
 
def calculate_subtree_sums(graph, weights, N):
    subtree_sum = defaultdict(int)
    dfs(1, -1, graph, weights, subtree_sum)
    return subtree_sum
 
def main():
    N, Q = map(int, input().split())
    weights = list(map(int, input().split()))
 
    # Initialize the tree as an adjacency list
    graph = defaultdict(list)
    for _ in range(N - 1):
        A, B = map(int, input().split())
        graph[A].append(B)
        graph[B].append(A)
 
    # Calculate subtree sums
    subtree_sum = calculate_subtree_sums(graph, weights, N)
 
    # Process queries
    for _ in range(Q):
        U, V = map(int, input().split())
        print(subtree_sum[U] - subtree_sum[V])
 
if __name__ == "__main__":
    main()