Competitions

# Exponentiation

# Happy sum

It is known that the number is happy, if its decimal notation contains only fours and sevens. For example, the numbers **4**, **7**, **47**, **7777** and **4744474** are happy.

Let **S** be the set of happy numbers, no less than **a** and no more than **b**: **S** = {**n** : **a** ≤ **n** ≤ **b**, **n** is happy}. Calculate the remainder of dividing by **1234567891** the next sum:

#### Input

Two integers **a** and **b** (**1** ≤ **a** ≤ **b** ≤ `10`

).^{18}

#### Output

Output the remainder of dividing the lucky sum by **1234567891**.

#### Explanation

`4`

+ ^{4}`7`

= ^{7}**823799**.

Input example #1

1 10

Output example #1

823799