N,K = map(int,input().split())
MOD = 10**9+7
A = list(range(2*N+1))
A[0] = 1
for i in range(3,2*N+1):
    A[i] = i*A[i-1]%MOD
B = [1]*(2*N+1)
B[2*N] = pow(A[2*N],MOD-2,MOD)
for i in range(2*N-1,1,-1):
    B[i] = (i+1)*B[i+1]%MOD
def comb(n,k):
    if k<0 or k>n:return 0
    return A[n]*B[k]*B[n-k]%MOD
if K>=N:
    P = K
    for i in range(1,N):
        P = P*(K-i)%MOD
    ans = 0
    for i in range(N):
        ans = (ans+P*pow(A[i],MOD-2,MOD)*pow(A[N-1-i],MOD-2,MOD))%MOD
        P = P*(K+i+1)*pow(K-N+1+i,MOD-2,MOD)%MOD
    ans = ans*pow(N,MOD-2,MOD)%MOD
else:
    ans = 0
    for i in range(N):
        ans = (ans+comb(N-1,i)*comb(K+i,N))%MOD
print(ans)