The Cursed Substring

Difficulty: 1900 3000 ms 128 MB

digit-dp

Count the integers in [L, R] whose decimal form CONTAINS the substring 13 (a 1 immediately followed by a 3).

Input: one line with two integers L and R.

Output: the count of integers containing '13'.

Constraints:

• 1 ≤ L ≤ R ≤ 10¹⁸

Sample Tests

1 20

1

13 13

1

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