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