Problem Description

Please count the number of times the digit $2$ appears in all integers within a given range $[L, R]$.

For example, given the range $[2, 22]$, the digit $2$ appears once in the number $2$, once in the number $12$, once in the number $20$, once in the number $21$, and twice in the number $22$. Therefore, the digit $2$ appears a total of $6$ times within this range.

Input Format

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

Output Format

The number of times the digit $2$ appears.

Sample Input and Output

Sample Input #1

2 22

Sample Output #1

6

Sample Input #2

2 100

Sample Output #2

20

Notes

$1 ≤ L ≤ R ≤ 100000$.

NOIP2010 Junior Group, Problem 1

见题面 Input 部分

见题面 Output 部分