from collections import Counter
 
 
def has_char_with_exactly_two_repeats(line):
    char_counts = Counter(line)
    return 2 in char_counts.values()
 
 
def main():
    print('Use Ctrl + C to exit the program.')
    try:
        while True:
            line = input().strip()
            if has_char_with_exactly_two_repeats(line):
                print(line)
    except EOFError:
        pass
    except KeyboardInterrupt:
        pass
 
 
main()
 
 

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