import sys
 
N, M = map(int, sys.stdin.readline().split())
 
lis =[]
for i in range(N):
    lis.append(sys.stdin.readline())
 
lis.sort()
 
ans = 0
ans_list = []
for i in range(M):
    tmp = sys.stdin.readline()
 
    start, end = 0, len(lis)-1
 
    while start <= end:
        mid = (start + end) // 2
        if lis[mid] == tmp:
            ans += 1
            ans_list.append(tmp)
            break
 
        if lis[mid] > tmp:
            start = mid + 1
        else:
            end = mid - 1
 
print(ans)
ans_list.sort()
for a in ans_list:
    print(a.rstrip())

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

MyA0Cm9oaGVucmllCmNoYXJsaWUKYmFlc2FuZ3dvb2sKb2JhbWEKYmFlc2FuZ3dvb2sKb2hoZW5yaWUKY2xpbnRvbg==

3 4
ohhenrie
charlie
baesangwook
obama
baesangwook
ohhenrie
clinton