Sets
Given numbers and .
Let be the set of all numbers from to .
A set is a subset of if for every , also belongs to . The empty set () is a subset of any set.
It is necessary to find the value of the function .
returns the number of subsets in the set .
where returns the sum where is a subset of .
Input
The first line contains two integers .
Output
It is necessary to output . Since the answer may be too large, output it modulo .
Examples
Note
In the first example, the set with element and , so =2 and .
In the second example, the set with elements and . .
Scoring
In this problem, there are conditional blocks. If your solution works correctly for certain constraints, it will receive a certain number of points. Note that the evaluation is still in the testing phase.
( points): ;
( points): , ;
( points): , ;
( points): without additional constraints.