Description

Count how many times the digit $2$ appears among all integers in the given range $[L, R]$.

For example, for the range $[2, 22]$, the digit $2$ appears 1 time in the number 2, 1 time in 12, 1 time in 20, 1 time in 21, and 2 times in 22, so the digit $2$ appears a total of 6 times in this range.

Input Format

$2$ positive integers $L$ and $R$, separated by a space.

Output Format

The number of occurrences of digit $2$.

2 22

6

2 100

20

Hint

Constraints: $1 ≤ L ≤ R ≤ 100000$.

NOIP 2010 Junior Problem 1.

Translated by ChatGPT 5