class Combinatorics: def __init__(self, n: int, mod: int) -> None: self.n = n self.mod = mod self.fa = [1] * (self.n + 1) self.fi = [1] * (self.n + 1) for i in range(1, self.n + 1): self.fa[i] = self.fa[i - 1] * i % self.mod self.fi[-1] = pow(self.fa[-1], self.mod - 2, self.mod) for i in range(self.n, 0, -1): self.fi[i - 1] = self.fi[i] * i % self.mod def comb(self, n: int, r: int) -> int: if n < r:return 0 if n < 0 or r < 0:return 0 return self.fa[n] * self.fi[r] % self.mod * self.fi[n - r] % self.mod def perm(self, n: int, r: int) -> int: if n < r:return 0 if n < 0 or r < 0:return 0 return self.fa[n] * self.fi[n - r] % self.mod def combr(self, n: int, r: int) -> int: if n == r == 0:return 1 return self.comb(n + r - 1, r) mod = 10 ** 9 + 7 n, k = map(int, input().split()) C = Combinatorics(n + k, mod) ans = 0 for i in range(n + 1): ans += C.comb(k + i, n) * C.comb(n - 1, i) ans %= mod print(ans)