n,k=map(int,input().split())

import sys
sys.setrecursionlimit(2147483647)

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p
p = 10**9+7 #割る数
N = 2*n+1  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans=1

if k>n:
    ans=cmb(n+n-1,n,p)

else:

    for i in range(1,k+1):
        ans+=(cmb(n, i, p)*cmb(n-1,n-i-1,p))%p
        
        #print(i,cmb(n, i, p),cmb(n-1,n-i-1,p))

print(ans%p)
     n,k=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split k import sys sys sys.setrecursionlimit(2147483647) sys.setrecursionlimit sys setrecursionlimit 2147483647 def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p cmb if (r < 0) or (n < r):
        return 0
     (r < 0) or (n < r) r < 0 r 0 n < r n r return 0 0 r = min(r, n - r) r min(r, n - r) min r n - r n r return fact[n] * factinv[r] * factinv[n-r] % p fact[n] * factinv[r] * factinv[n-r] % p fact[n] * factinv[r] * factinv[n-r] fact[n] * factinv[r] fact[n] fact n factinv[r] factinv r factinv[n-r] factinv n-r n r p n n r r p p p = 10**9+7 p 10**9+7 10**9 10 9 7 N = 2*n+1 N 2*n+1 2*n 2 n 1 fact = [1, 1] fact [1, 1] 1 1 factinv = [1, 1] factinv [1, 1] 1 1 inv = [0, 1] inv [0, 1] 0 1 for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p) i range(2, N + 1) range 2 N + 1 N 1 fact.append((fact[-1] * i) % p) fact.append fact append (fact[-1] * i) % p fact[-1] * i fact[-1] fact -1 i p inv.append((-inv[p % i] * (p // i)) % p) inv.append inv append (-inv[p % i] * (p // i)) % p -inv[p % i] * (p // i) -inv[p % i] inv[p % i] inv p % i p i p // i p i p factinv.append((factinv[-1] * inv[-1]) % p) factinv.append factinv append (factinv[-1] * inv[-1]) % p factinv[-1] * inv[-1] factinv[-1] factinv -1 inv[-1] inv -1 p ans=1 ans 1 if k>n:
    ans=cmb(n+n-1,n,p)

else:

    for i in range(1,k+1):
        ans+=(cmb(n, i, p)*cmb(n-1,n-i-1,p))%p
        
        #print(i,cmb(n, i, p),cmb(n-1,n-i-1,p)) k>n k n ans=cmb(n+n-1,n,p) ans cmb(n+n-1,n,p) cmb n+n-1 n+n n n 1 n p for i in range(1,k+1):
        ans+=(cmb(n, i, p)*cmb(n-1,n-i-1,p))%p
        
        #print(i,cmb(n, i, p),cmb(n-1,n-i-1,p)) i range(1,k+1) range 1 k+1 k 1 ans+=(cmb(n, i, p)*cmb(n-1,n-i-1,p))%p ans (cmb(n, i, p)*cmb(n-1,n-i-1,p))%p cmb(n, i, p)*cmb(n-1,n-i-1,p) cmb(n, i, p) cmb n i p cmb(n-1,n-i-1,p) cmb n-1 n 1 n-i-1 n-i n i 1 p p print(ans%p) print ans%p ans p def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p cmb factinv = [1, 1] [1, 1] factinv p = 10**9+7 10**9+7 p inv = [0, 1] [0, 1] inv ans=1 1 ans fact = [1, 1] [1, 1] fact ans+=(cmb(n, i, p)*cmb(n-1,n-i-1,p))%p (cmb(n, i, p)*cmb(n-1,n-i-1,p))%p ans N = 2*n+1 2*n+1 N ans=cmb(n+n-1,n,p) cmb(n+n-1,n,p) ans k=map(int,input().split()) map(int,input().split()) k n,k=map(int,input().split()) map(int,input().split()) n
n,k=map(int,input().split())

import sys
sys.setrecursionlimit(2147483647)

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p
p = 10**9+7 #割る数
N = 2*n+1  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

ans=1

if k>n:
    ans=cmb(n+n-1,n,p)

else:

    for i in range(1,k+1):
        ans+=(cmb(n, i, p)*cmb(n-1,n-i-1,p))%p
        
        #print(i,cmb(n, i, p),cmb(n-1,n-i-1,p))

print(ans%p)
    
