John's Test
Small John is testing numbers using two integers, A and B. For any integer X, if A ≤ X ≤ B, then X passes John's test. If not, John rearranges the digits of X to form a new integer Y. He constructs Y by taking the first digit of X, then the last digit, followed by the second digit, the second-to-last digit, and so on, until all digits are used. For instance, if X = 1234567, then Y = 1726354, and if X = 1020, then Y = 1002. If A ≤ Y ≤ B, then X passes the test; otherwise, it does not.
Your task is to determine how many positive integers pass John's test.
Input
Two integers A and B, separated by a space.
Output
The count of positive integers that pass the test.
Constraints
1 ≤ A ≤ B ≤ 1000000000000000000 (10^18).
Notes
In the first example, the numbers 98, 99, 100, 101, 102, 110, and 120 pass John's test.