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题库练习 Different Subsets For All Tuples

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A10269 | $Different Subsets For All Tuples$

时间限制1s

内存限制256MB

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题目描述

For a sequence $a$ of $n$ integers between $1$ and $m$ , inclusive, denote $f(a)$ as the number of distinct subsequences of $a$ (including the empty subsequence). You are given two positive integers $n$ and $m$ . Let $S$ be the set of all sequences of length $n$ consisting of numbers from $1$ to $m$ . Compute the sum $f(a)$ over all $a$ in $S$ modulo $10^{9}+7$ .

输入格式

The only line contains two integers $n$ and $m$ ( $1<=n,m<=10^{6}$ ) — the number of elements in arrays and the upper bound for elements.

输出格式

Print the only integer $c$ — the desired sum modulo $10^{9}+7$ .

输入输出样例

输入 #1

1 3

输出 #1

输入 #2

2 2

输出 #2

输入 #3

3 3

输出 #3

C++ 编辑器

输入

输出