N, p = map(int, input().split())
mod = 10 ** 9 + 7

A = [0, 1]

for i in range(N - 2):
    
    A += [(A[-1] * p + A[-2]) % mod]
    
a = A.copy()

for i in range(1, N):
    a[i] += a[i - 1]
    a[i] %= mod
    
ans = 0

for i in range(N):
    
    ans += A[i] * a[i] % mod
    ans %= mod
    
    
print(ans)