#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e6 + 10, MAXM = 4e6 + 10;
const int INF = INT_MAX, SINF = 0x3f3f3f3f;
const long long llINF = LLONG_MAX;
const int MOD = 1e9 + 7, mod = 998244353;
const int inv2 = 5e8 + 4;
int n, m;
long long fac[MAXN], inc[MAXN];
long long ksm(long long x, long long v) {
  long long ans = 1;
  while (v) {
    if (v & 1) (ans *= x) %= MOD;
    (x *= x) %= MOD;
    v >>= 1;
  }
  return ans;
}
int main() {
  scanf("%d%d", &n, &m);
  long long ans = 0;
  for (int i = 1; i <= n; i++)
    (ans += ksm(m, i) * ksm(2 * m - 1, n - i) % MOD) %= MOD;
  cout << (ans + ksm(m, n)) % MOD;
  return 0;
}

### Prompt

Please formulate a CPP solution to the following problem:

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

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

Output

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

Examples

Input

1 3


Output

6


Input

2 2


Output

14


Input

3 3


Output

174

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e6 + 10, MAXM = 4e6 + 10;
const int INF = INT_MAX, SINF = 0x3f3f3f3f;
const long long llINF = LLONG_MAX;
const int MOD = 1e9 + 7, mod = 998244353;
const int inv2 = 5e8 + 4;
int n, m;
long long fac[MAXN], inc[MAXN];
long long ksm(long long x, long long v) {
  long long ans = 1;
  while (v) {
    if (v & 1) (ans *= x) %= MOD;
    (x *= x) %= MOD;
    v >>= 1;
  }
  return ans;
}
int main() {
  scanf("%d%d", &n, &m);
  long long ans = 0;
  for (int i = 1; i <= n; i++)
    (ans += ksm(m, i) * ksm(2 * m - 1, n - i) % MOD) %= MOD;
  cout << (ans + ksm(m, n)) % MOD;
  return 0;
}

```