def dfs(node, parent):
    global ans, beauty, visited
    visited[node] = True
    for child in graph[node]:
        if child != parent:
            if visited[child]:
                ans = 1
                return
            beauty += values[child]
            dfs(child, node)
            if ans:
                return
            beauty -= values[child]


t = int(input())
for _ in range(t):
    n = int(input())
    values = list(map(int, input().split()))
    graph = {i+1: [] for i in range(n)}
    for _ in range(n-1):
        a, b = map(int, input().split())
        graph[a].append(b)
        graph[b].append(a)

    visited = [False] * (n+1)
    ans = 0
    for i in range(1, n+1):
        if not visited[i]:
            beauty = values[i-1]
            dfs(i, 0)
            if ans:
                break

    if ans:
        print("NEM")
        bad_tour = []
        visited = [False] * (n+1)
        for i in range(1, n+1):
            if visited[i]:
                break
            visited[i] = True
            if values[i-1] == -1:
                bad_tour.append(i)
            for child in graph[i]:
                visited[child] = True
                if values[child-1] == -1:
                    bad_tour.append(child)
            if sum(values[i-1] for i in bad_tour) < 0:
                break
        print(len(bad_tour))
        print(*bad_tour)
    else:
        print("IGEN")