nan + nan = 2nan

코드 입력 test_case = int(input()) cnt = 0 for _ in range(1, test_case+1): test_ = input() val_word = [] before_alphabet = '' while True: if len(test_) >= 2: if test_[0] not in val_word: val_word.append(test_[0]) before_alphabet = test_[0] test_ = test_[1:] elif test_[0] not in val_word: val_word.append(test_[0]) before_alphabet = test_[0] test_ = test_[1:] elif test_[0] in val_word and before_alpha..