1
Description
Count how many occurrence of number 1 between two numbers \$[a, b]\$.
For example from 1 to 100 it should be 21:
1, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 31, 41, 51, 61, 71, 81, 91
The number 1 is repeated 20 times.
Rules
Each number in the input list is guaranteed is an integer ...