Hubert is one of the security guards employed by a jewelry company to work at night. (1) is on duty by turns. It has been less than 100 days since Hubert took office for the first time. (2) Hubert's first duty and last duty only met on two Sundays during the duty. (3) Hubert is on duty for the first time and the last time on the same day in different months. (4) Hubert's first duty and last duty are on the same day of the same month. In which month of the year was Hubert on duty for the first time? According to the answer (1), the distance between Hubert's first duty and his last duty is less than 100 days. According to (2), the number of days between Hubert's first duty and his latest duty must be a multiple of 7. According to (3) and (4), Hubert will not be on duty for the first time in February, because no other month has the same number of days as February. Therefore, the distance between Hubert's first duty and his last duty exceeded 28 days. According to the above points, the number of days between Hubert's first duty and his last duty must be one of the following: 35, 42, 49, 56, 63, 70, 84, 9 1, 98. Judging from these ten possibilities, Hubert's first duty and last duty were separated by more than a month, less than four months. Therefore, according to (3), Hubert's first shift and the last shift are exactly two or three months apart. Starting from the left column and starting from the left column, consecutive months, two months and three months 1 month 3 1 59 or 60 90 or 91February 28 or 29 59 or 60 89 or 91March 316/kloc- 38+0 6192 June 30th 6192 July 3rd162 92 August 3rd16192 September 30th 619/kloc. 1 62 90 or 9 1 In the above table, only 9 1 may appear in the above ten kinds. So the distance between Hubert's first duty and his last duty is 9 1 day. Results There were four possibilities for the first and last months on duty: the first month on duty, the last month on duty, 1, 1 month (3 1 day), April (30 days), July (3/kloc-0).

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