KöMaL 2026 K899

Anna has written all the positive two-digit numbers on the blackboard once. Boglárka has erased Anna's numbers one by one and replaced them with the numbers obtained by subtracting their first digits from the second. For example, $26$ is replaced with $6-2=4$ and $37$ is replaced with $3-7=-4$. Find the sum of Boglárka's numbers.