Digit Sum Divisible by 7

Difficulty: 1900 4000 ms 128 MB

digit-dp

Count integers in [L, R] whose digit sum is divisible by 7.

Input: one line with two integers L and R.

Output: the count in [L, R].

Constraints:

• 1 ≤ L ≤ R ≤ 10¹⁸

Sample Tests

1 30

3

10 50

4

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