n, k = map(int, input().split())
mod = 10**9 + 7

# nは任意の数に置き換え可能
fact = [1] * (n + 1)
inv = [1] * (n + 1)
finv = [1] * (n + 1)
for i in range(2, n + 1):
    fact[i] = fact[i - 1] * i % mod
    inv[i] = mod - inv[mod % i] * (mod // i) % mod
    finv[i] = finv[i - 1] * inv[i] % mod

def comb(a, b):
    return fact[a] * finv[b] * finv[a - b] % mod
def extgcd(a, b):
    if b != 0:
        d, y, x = extgcd(b, a % b)
        y -= (a // b) * x
        return d, x, y
    return a, 1, 0
def inverse(a, m):
    d, x, _ = extgcd(a, m)
    if d != 1:
        return -1
    return x % m

ans = 0
cnt = 1
if k >= n:
    for i in range(1, n + 1):
        cnt *= k - i + 1
        cnt *= inv[i]
        cnt %= mod
    ans += cnt

for i in range(1, n):
    if k + i > n:
        cnt *= k + i
        cnt *= inverse(k + i - n, mod)
        cnt %= mod
        ans += cnt * comb(n - 1, i) % mod
        ans %= mod
    elif k + i == n:
        ans += cnt * comb(n - 1, i) % mod
        ans %= mod
print(ans)