#define TEMPLATE_USED
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef pair<ll,ll> pl;
typedef vector<pl> vp;
const ll INF=1001001001;
const ll LINF=1001001001001001001;
const ll D4[]={0,1,0,-1,0};
const ll D8[]={0,1,1,0,-1,-1,1,-1,0};
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) for(ll i=0;i<(n);++i)
#define _rep3(i,a,b) for(ll i=(a);i<(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2)(__VA_ARGS__)
#define _repe2(i,n) for(ll i=0;i<=(n);++i)
#define _repe3(i,a,b) for(ll i=(a);i<=(b);++i)
#define repe(...) _overload3(__VA_ARGS__,_repe3,_repe2)(__VA_ARGS__)
#define _rrep2(i,n) for(ll i=(n)-1;i>=0;i--)
#define _rrep3(i,a,b) for(ll i=(b)-1;i>=(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
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(b<a){a=b;return 1;}return 0;}
template<class T>
using pq=priority_queue<T,vector<T>,greater<T>>;

void solve();

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    solve();
}

#ifndef TEMPLATE_USED
#include "../template/template.hpp"
#endif

template<int m>
struct MInt{
    //static int m;

    ll x;
    MInt(ll x=0):x((x%m+m)%m){}

    MInt operator-()const{return MInt(-x);}
    MInt operator+(const MInt &p)const{return MInt(*this)+=p;}
    MInt operator-(const MInt &p)const{return MInt(*this)-=p;}
    MInt operator*(const MInt &p)const{return MInt(*this)*=p;}
    MInt operator/(const MInt &p)const{return MInt(*this)/=p;}

    MInt &operator+=(const MInt &p){
        if((x+=p.x)>=m)x-=m;
        return *this;
    }
    MInt &operator-=(const MInt &p){
        if((x+=m-p.x)>=m)x-=m;
        return *this;
    }
    MInt &operator*=(const MInt &p){
        (x*=p.x)%=m;
        return *this;
    }
    MInt &operator/=(const MInt &p){
        return *this*=p.inv();
    }

    MInt pow(ll n)const{
        MInt ret(1),mul(x);
        while(n){
            if(n&1)ret*=mul;
            mul*=mul;
            n>>=1;
        }
        return ret;
    }
    MInt inv()const{
        //return pow(m-2);
        int a=x,b=m,u=1,v=0,t;
        while(b){
            t=a/b;
            swap(a-=t*b,b);
            swap(u-=t*v,v);
        }
        return MInt(u);
    }

    friend ostream& operator<<(ostream& os,const MInt& a) {return os<<a.x;}
};
//int MInt::m=0;
using mint=MInt<(ll)1e9+7>;

#ifndef TEMPLATE_USED
#include "../template/template.hpp"
#include "../math/mint.hpp"
#endif

struct Combination{
    vector<mint> f,rev;
    Combination(int n):f(n+1),rev(n+1){
        f[0]=1;
        repe(i,1,n)f[i]=f[i-1]*i;
        rev[n]=mint(1)/f[n];
        rrep(i,n)rev[i]=rev[i+1]*(i+1);
    }
    mint p(int n,int k){return k<0||n<k?0:f[n]*rev[n-k];}
    mint c(int n,int k){return k<0||n<k?0:f[n]*rev[n-k]*rev[k];}
    mint h(int n,int r){return n<0||r<0?0:(!r?1:c(n+r-1,r));}
};

void solve(){
    ll n,k;cin>>n>>k;

    chmin(k,n-1);

    Combination comb(400005);

    mint ans=0;
    repe(i,k){
        ans+=comb.c(n,i)*comb.h(n-i,i);
    }
    cout<<ans<<endl;
}

Measured memory_bytes: 6528