문제 원문에서의 Output은

Generate a line of output for each telephone number that appears more than once in any form. The
line should give the telephone number in standard form, followed by a space, followed by the number
of times the telephone number appears in the directory. Arrange the output lines by telephone number
in ascending lexicographical order. If there are no duplicates in the input print the line:
No duplicates. 

Generate a line of output for each telephone number that appears more than once in any form. The line should give the telephone number in standard form, followed by a space, followed by the number of times the telephone number appears in the directory. Arrange the output lines by telephone number in ascending lexicographical order. If there are no duplicates in the input print the line:

로 명시되어 있습니다. 즉,  중복이 없을 시에 "No duplicates."를 출력하라는 조건이 누락되었습니다.