def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 2*(10**5)+1
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )
a,b=map(int,input().split())
c=min(a,b)
s=0
for i in range(0,c+1):
    s+=cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7)
print(s%(10**9+7)) def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod cmb if ( r<0 or r>n ):
        return 0
     r<0 or r>n r<0 r 0 r>n r n return 0 0 r = min(r, n-r) r min(r, n-r) min r n-r n r return g1[n] * g2[r] * g2[n-r] % mod g1[n] * g2[r] * g2[n-r] % mod g1[n] * g2[r] * g2[n-r] g1[n] * g2[r] g1[n] g1 n g2[r] g2 r g2[n-r] g2 n-r n r mod n n r r mod mod mod = 10**9+7 mod 10**9+7 10**9 10 9 7 N = 2*(10**5)+1 N 2*(10**5)+1 2*(10**5) 2 10**5 10 5 1 g1 = [1, 1] g1 [1, 1] 1 1 g2 = [1, 1] g2 [1, 1] 1 1 inverse = [0, 1] inverse [0, 1] 0 1 for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod ) i range( 2, N + 1 ) range 2 N + 1 N 1 g1.append( ( g1[-1] * i ) % mod ) g1.append g1 append ( g1[-1] * i ) % mod g1[-1] * i g1[-1] g1 -1 i mod inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod ) inverse.append inverse append ( -inverse[mod % i] * (mod//i) ) % mod -inverse[mod % i] * (mod//i) -inverse[mod % i] inverse[mod % i] inverse mod % i mod i mod//i mod i mod g2.append( (g2[-1] * inverse[-1]) % mod ) g2.append g2 append (g2[-1] * inverse[-1]) % mod g2[-1] * inverse[-1] g2[-1] g2 -1 inverse[-1] inverse -1 mod a,b=map(int,input().split()) a map(int,input().split()) map int input().split() ().split () input split b c=min(a,b) c min(a,b) min a b s=0 s 0 for i in range(0,c+1):
    s+=cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7) i range(0,c+1) range 0 c+1 c 1 s+=cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7) s cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7) cmb(a,i,10**9+7) cmb a i 10**9+7 10**9 10 9 7 cmb(a-1,i,10**9+7) cmb a-1 a 1 i 10**9+7 10**9 10 9 7 print(s%(10**9+7)) print s%(10**9+7) s 10**9+7 10**9 10 9 7 g2 = [1, 1] [1, 1] g2 mod = 10**9+7 10**9+7 mod a,b=map(int,input().split()) map(int,input().split()) a b=map(int,input().split()) map(int,input().split()) b s+=cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7) cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7) s g1 = [1, 1] [1, 1] g1 s=0 0 s inverse = [0, 1] [0, 1] inverse def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod cmb N = 2*(10**5)+1 2*(10**5)+1 N c=min(a,b) min(a,b) c
def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 2*(10**5)+1
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )
a,b=map(int,input().split())
c=min(a,b)
s=0
for i in range(0,c+1):
    s+=cmb(a,i,10**9+7)*cmb(a-1,i,10**9+7)
print(s%(10**9+7))