Mimi has just won two raffle tickets for the Polar Express! Unfortunately, there is just one obstacle in the way — the skill testing question!

Let us define $\mathrm{S}(x)$ to be the sum of digits of $x$. Given two positive integers, $L$ and $R$, compute the number of distinct values of $\mathrm{S}(x)$, for $x=L,L+1,\dots ,R$.

Mimi has agreed to give you the other ticket if you help her solve this problem. Can you do it?

Constraints

Subtask 1 [10%]

$1\le L\le R\le {10}^5$

Subtask 2 [90%]

$1\le L\le R\le {10}^{18}$

Input Specification

The first and only line of input will contain two space separated integers, $L$ and $R$.

Output Specification

A single integer, the number of distinct values of $\mathrm{S}(x)$.

Sample Input

19 28

Sample Output

9