N, p = map(int, input().split())
MOD = 1000000007

a = [0] * N 
a[0] = 0
a[1] = 1
for i in range(2, N):
  a[i] = p * a[i-1] + a[i-2]

revcum = [0] * N
c = 0
for i, v in enumerate(a[::-1]):
    c += v
    revcum[i] = c 

ans = 0
for i, j in zip(a, revcum[::-1]): 
    ans += i * j % MOD

print(ans % MOD)