import sys
n,m = map(int,sys.stdin.readline().strip().split())
li = set([])
ans = []
for i in range(n):
listenx = sys.stdin.readline().strip()
li.add(listenx)
for i in range(m):
lookx = sys.stdin.readline().strip()
if lookx in li:
ans.append(lookx+'\n')
ans.sort()
print(len(ans))
print(''.join(ans))