[백준] 1764번: 듣보잡

백준 1764번

import sys

N, M = map(int, sys.stdin.readline().rstrip().split())
dict_list = {}
result = []
for _ in range(N + M):
    name = sys.stdin.readline().rstrip()
    if name in dict_list:
        result.append(name)
    else:
        dict_list[name] = 1
result.sort()
print(len(result))
for val in result:
    print(val)