#include<bits/stdc++.h>
using namespace std;

using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

vector<ll> fact, factinv, inv;
ll mod = 1e9 + 7;
void prenCkModp(ll n) {
	fact.resize(n + 5);
	factinv.resize(n + 5);
	inv.resize(n + 5);
	fact.at(0) = fact.at(1) = 1;
	factinv.at(0) = factinv.at(1) = 1;
	inv.at(1) = 1;
	for (ll i = 2; i < n + 5; i++) {
		fact.at(i) = (fact.at(i - 1) * i) % mod;
		inv.at(i) = mod - (inv.at(mod % i) * (mod / i)) % mod;
		factinv.at(i) = (factinv.at(i - 1) * inv.at(i)) % mod;
	}

}
ll nCk(ll n, ll k) {
	if (n < k) return 0;
	return fact.at(n) * (factinv.at(k) * factinv.at(n - k) % mod) % mod;
}
ll inva(ll N) {
    ll a = N, b = mod, c = 1, d = 0;
    while (b > 0) {
        ll t = a / b;
        a -= t * b;
        swap(a, b);
        c -= t * d;
        swap(c, d);

    }
    c %= mod;
    if (c < 0)c += mod;
    return c;

}

int main() {
   ll N,K;
   cin>>N>>K;
   prenCkModp(N+3);
   ll an=0;
   ll p=1;
   rep(i,N){
       p*=(K+N-1-i);
       p%=mod;
       p*=inv[i+1];
       p%=mod;
   }
   rep(k,min(N,K)){
       an+=p;
       an%=mod;
       //cout<<p<<endl;
       p*=(K-1-k);
       p%=mod;
       p*=inva(K+N-1-k);
       p%=mod;
       p*=inva(k+1);
       p%=mod;
       p*=(N-1-k);
       p%=mod;
       
   }
   cout<<an<<endl;
}