#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------


int N,K;
const ll mo=1000000007;

const int NUM_=1400001;
static ll fact[NUM_+1],factr[NUM_+1],inv[NUM_+1];
map<int,ll> F;

ll comb(ll N_, ll C_) {
	if(C_<0 || C_>N_) return 0;
	return factr[C_]*fact[N_]%mo*factr[N_-C_]%mo;
}


ll modpow(ll a, ll n = mo-2) {
	ll r=1;a%=mo;
	while(n) r=r*((n%2)?a:1)%mo,a=a*a%mo,n>>=1;
	return r;
}

ll comb2(ll N_, ll C_) {
	if(C_<0 || C_>N_) return 0;
	return F[N_]*factr[C_]%mo*modpow(F[N_-C_])%mo;
}


void solve() {
	int i,j,k,l,r,x,y; string s;

	inv[1]=fact[0]=factr[0]=1;
	for (int i=2;i<=NUM_;++i) inv[i] = inv[mo % i] * (mo - mo / i) % mo;
	for (int i=1;i<=NUM_;++i) fact[i]=fact[i-1]*i%mo, factr[i]=factr[i-1]*inv[i]%mo;
	
	cin>>N>>K;
	
	ll ret=0;
	
	if(K<=1000000) {
		for(i=0;i<=N-1;i++) {
			int a=K-1-i;
			if(a<0) continue;
			ret+=comb(a+N,N)*comb(N-1,i)%mo;
		}
	}
	else {
		F[K-500000]=1;
		for(i=K-500000+1;i<=K+500000;i++) F[i]=F[i-1]*i%mo;
		for(i=0;i<=N-1;i++) {
			int a=K-1-i;
			if(a<0) continue;
			ret+=comb2(a+N,N)*comb(N-1,i)%mo;
		}
	}
	cout<<ret%mo<<endl;
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}