#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
// #include<boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision;

using lnt = long long;
using Real = long double;

#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define REP(i, n) for(lnt i=0;i<(n);++i)
#define RANGE(i, a, b) for(lnt i=(a);i<(b);++i)
#define RREP(i, n) for(lnt i=(n)-1;i>= 0;--i)

#define ln '\n'
#define pb push_back
#define eb emplace_back
#define pque priority_queue
#define umap unordered_map
#define uset unordered_set
#define dcout cout<<fixed<<setprecision(20)
#define summon_tourist cin.tie(0);ios::sync_with_stdio(false)

constexpr int dx[]={1,0,-1,0,1,1,-1,-1}, dy[]={0,-1,0,1,1,-1,1,-1};
constexpr Real eps = 1e-9; const Real pi = acosl(-1);
constexpr lnt BIG = INT_MAX/10, BBIG = LLONG_MAX/10;

template<class T> inline T GCD(T a,T b){T c;while(b!=0){c=a%b;a=b;b=c;}return a;}
template<class T> inline T LCM(T a,T b){T c=GCD(a,b);a/=c;return a*b;}
template<class T> inline T nCr(T a,T b){T i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
template<class T> inline T nHr(T a,T b){return nCr(a+b-1,b);}
template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}

using pint = pair<int, int>; using plnt = pair<lnt, lnt>;
using vint = vector<int>; using vlnt = vector<lnt>;
constexpr lnt MOD = 1e9+7;

lnt fact[500000], invfact[500000];

lnt invmod(lnt a, lnt p){ // a^-1 mod p
	lnt b = p, u = 1, v = 0;
	while(b){
		lnt t = a / b;
		a -= t*b; swap(a, b);
		u -= t*v; swap(u, v);
	}
	u %= p;
	if(u < 0) u += p;
	return u;
}

void factmod(lnt m){
	fact[0] = invfact[0] = 1;
	for(lnt i = 1; i < 500000; i++){
		fact[i] = (fact[i-1] * i) % m;
		invfact[i] = (invfact[i-1] * invmod(i, m)) % m;
	}
}

lnt nCrmod(lnt n, lnt r, lnt m){
	return (((fact[n] * invfact[r]) % m) * invfact[n-r]) % m;
}

int main(){
    summon_tourist;

    using namespace atcoder;
    using mint = modint1000000007;
    factmod(MOD);
    lnt N, K; cin >> N >> K;
    mint ans = 0;
    for(lnt eq = 0; eq <= N-1; eq++){
        lnt A = K + eq+2 - 1;
        if(A-1 < N) continue;
        mint plus = nCrmod(N-1, eq, MOD);
        ans += plus * nCrmod(A-1, N, MOD);
    }
    cout << ans.val() << ln;
}