from sys import stdin
from collections import defaultdict

def csunyakereso(graf, csunyak, eddigi_ut):
	mehet_tovabb = len(eddigi_ut) < 2
	for kovetkezo in graf[eddigi_ut[-1]]:
		if kovetkezo in eddigi_ut:
			continue
		if kovetkezo in csunyak:
			print('NEM')
			print(len(eddigi_ut)+1)
			print(' '.join(str(x) for x in eddigi_ut + (kovetkezo,)))
			return True
		if mehet_tovabb:
			if csunyakereso(graf, csunyak, eddigi_ut + (kovetkezo,)):
				return True
	return False

T = int(stdin.readline())
for _ in range(T):
	N = int(stdin.readline())
	utak = defaultdict(set)
	sz = [int(x) for x in stdin.readline().split()]
	csunyak = set(i+1 for i, x in enumerate(sz) if x == -1)
	if len(csunyak) < 2:
		for _ in range(N-1):
			stdin.readline()
		print('IGEN')
		continue
	for _ in range(N-1):
		honnan, hova = [int(x) for x in stdin.readline().split()]
		utak[honnan].add(hova)
		utak[hova].add(honnan)
	for cs in csunyak:
		if csunyakereso(utak, csunyak, (cs,)):
			break
	else:
		print('IGEN')
	# print(sz)
	# print(csunyak)
	# print(utak)