# sisendi korrektsuse kontrollija

import sys

fi = open(sys.argv[1], 'rt')
fo = open(sys.argv[2], 'wt')

(n, k) = map(int, fi.readline().strip().split())
if 1 > n or n > 500000:
	sys.exit('N out of range')
if 1 > k or k > n:
	sys.exit('K out of range')
fo.write('{0} {1}\n'.format(n, k))

g = [[] for i in range(n)]
for i in range(n - 1):
	(u, v) = map(int, fi.readline().strip().split())
	if 1 > u or u > n:
		sys.exit('U[{0}] out of range'.format(i + 1))
	if 1 > v or v > n:
		sys.exit('V[{0}] out of range'.format(i + 1))
	g[u - 1].append(v - 1)
	g[v - 1].append(u - 1)
	fo.write('{0} {1}\n'.format(u, v))

cc = map(int, fi.readline().strip().split())
if len(cc) <> k:
	sys.exit('Wrong number of C values')
for i, c in enumerate(cc):
	if 1 > c or c > n:
		sys.exit('C[{0}] out of range'.format(i + 1))
fo.write('{0}\n'.format(' '.join(map(str, cc))))

fi.close()
fo.close()

# teedegraaf peab olema sidus

h = [0 for i in range(n)]
q = [0]
while len(q) > 0:
	i = q.pop()
	h[i] = 1
	for j in g[i]:
		if h[j] == 0:
			q.append(j)
if sum(h) <> n:
	sys.exit('Road network not connected')

# turniiril osalevad linnad peavad olema paarikaupa erinevad

cc.sort()
d = 0
for c in cc:
	if c == d:
		sys.exit('Duplicate tournament participant {0}\n'.format(c))
	d = c