CF1538F Interesting Function

You are given two integers $ l $ and $ r $ , where $ l < r $ . We will add $ 1 $ to $ l $ until the result is equal to $ r $ . Thus, there will be exactly $ r-l $ additions performed. For each such addition, let's look at the number of digits that will be changed after it. For example: - if $ l=909 $ , then adding one will result in $ 910 $ and $ 2 $ digits will be changed; - if you add one to $ l=9 $ , the result will be $ 10 $ and $ 2 $ digits will also be changed; - if you add one to $ l=489999 $ , the result will be $ 490000 $ and $ 5 $ digits will be changed. Changed digits always form a suffix of the result written in the decimal system. Output the total number of changed digits, if you want to get $ r $ from $ l $ , adding $ 1 $ each time.

The first line contains an integer $ t $ ( $ 1 \le t \le 10^4 $ ). Then $ t $ test cases follow. Each test case is characterized by two integers $ l $ and $ r $ ( $ 1 \le l < r \le 10^9 $ ).

For each test case, calculate the total number of changed digits if you want to get $ r $ from $ l $ , adding one each time.