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

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

S=0
ANS=0
for i in range(N):
    S+=A[i]
    ANS+=S*A[i]
    S%=mod
    ANS%=mod

print(ANS)