7.2. Students in the seventh grade send each other New Year's stickers on Telegram. It is known that exactly 26 people received at least one sticker, exactly 25 - at least two stickers, ..., exactly 1 - at least 26 stickers. How many stickers did the students in this class receive in total, if it is known that no one received more than 26 stickers? (find all possible answers and prove that there are no others)
# Answer: 351

Solution: Note that exactly 1 sticker was received by one person, as it is precisely in this case that the difference between those who received at least 1 and those who received at least 2. Similarly, one person received exactly $2, 3, \ldots, 26$ stickers, so the total number of stickers is $1+\ldots+26=351$.

Criteria: Only the answer - 0 points.

Answer with verification that it is possible - 1 point.

Answer written in an open form (ellipsis left) or arithmetic error - minus 1 point.