Question 42
On a blackboard Daniel wrote, from top to bottom, a list of positive integers less than or equal to $10$. Next to each number on Daniel's list, Martin wrote down the number of times that number appeared on Daniel's list, thus obtaining a list of the same length.
If you read Martin's list from the bottom up you get the same list of numbers that Daniel wrote from the top down. Find the maximum length that Daniel's list can have.
If you read Martin's list from the bottom up you get the same list of numbers that Daniel wrote from the top down. Find the maximum length that Daniel's list can have.