n,k=map(int,input().split())
mod=10**9+7
fac=[0]*(2*n+2)
cnt=1
fac[0]=1
for i in range(2*n+1):
    cnt*=k+n-i
    cnt%=mod
    fac[i+1]=cnt
fac2=[0]*(n+2)
fac2[0]=1
cnt=1
for i in range(n+1):
    cnt*=i+1
    cnt%=mod
    fac2[i+1]=cnt
gya=[0]*(n+2)
cnt=1
gya[0]=1
for i in range(n+1):
    cnt*=pow(i+1,mod-2,mod)
    cnt%=mod
    gya[i+1]=cnt
ans=0
for i in range(n):
    if i<=k-1:
        num=fac2[n-1]*gya[n-i-1]%mod
        num*=gya[i]
        num%=mod
        # k+n-1-i C n
        num2=(fac[i+n+1]*pow(fac[i+1],mod-2,mod))%mod
        num2*=gya[n]
        num2%=mod
        ans+=num*num2%mod
        ans%=mod
print(ans)