#include <iostream>
#include <vector>
#include <algorithm>
#include <atcoder/modint>
using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(n); i++)


using m32 = atcoder::modint1000000007;


int main() {
    i64 N,K; cin >> N >> K;

    K--;

    m32 rComb = 1;
    for(int i=1; i<=N; i++) rComb /= i;
    for(int i=0; i<N; i++) rComb *= N+K-i;
    m32 lComb = 1;

    m32 ans = lComb * rComb;

    for(int n=1; n<=min(N-1,K); n++){
        lComb *= (N-n);
        lComb /= n;
        rComb *= K-n+1;
        rComb /= N+K-n+1;
        ans += lComb * rComb;
    }

    cout << ans.val() << endl;
    return 0;
}


struct ios_do_not_sync{
    ios_do_not_sync(){
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} ios_do_not_sync_instance;