2365.Different Subsets For All Tuples

Time Limit: 1s Memory Limit: 256MB

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 109+7.

Input Format(From the terminal/stdin)

The only line contains two integers n and m (1 \le n,m \le 106) - the number of elements in arrays and the upper bound for elements.

Output Format(To the terminal/stdout)

Print the only integer c - the desired sum modulo 109+7.

Sample Input 1

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1 3
 · \n

Sample Output 1

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6
 \n

Sample Input 2

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2 2
 · \n

Sample Output 2

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14
  \n

Sample Input 3

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3 3
 · \n

Sample Output 3

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174
   \n

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