mod = 10 ** 9 + 7

N, p = map(int, input().split())
A = [0, 1]
for i in range(N - 2):
    v = p * A[-1] + A[-2]
    A.append(v % mod)

Acum = [0]
for a in A:
    v = Acum[-1] + a
    Acum.append(v % mod)

ans = 0
Asum = Acum[-1]
for i, a in enumerate(A):
    v = a * (Asum - Acum[i]) % mod
    ans = (ans + v) % mod

print(ans)