mod=10**9+7
n,p=map(int,input().split())
if n==1:print(0);exit()
if n==2:print(1);exit()
s=1
a0,a1=0,1
ans=1
for i in range(2,n):
  a0,a1=a1,a0+p*a1
  a1%=mod
  s+=a1
  s%=mod
  ans+=s*a1
  ans%=mod
print(ans)