#include "bits/stdc++.h"
using namespace std;
#define int long long
#define REP(i,n) for(int i = 0;i < (int)(n);++i)
#define RREP(i,n) for(int i = (int)n-1;i >= 0;--i)
#define FOR(i,s,n) for(int i = s;i < (int)n;++i)
#define RFOR(i,s,n) for(int i = (int)n-1;i >= s;--i)
#define ALL(a) a.begin(),a.end()
#define IN(a, x, b) (a<=x && x<b)
template<class T>inline void out(T t){cout<<t<<"\n";}
template<class T,class... Ts>inline void out(T t,Ts... ts){cout<<t<<" ";out(ts...);}
template<class T>inline bool CHMAX(T&a,T b){if(a<b){a = b;return true;}return false;}
template<class T>inline bool CHMIN(T&a,T b){if(a>b){a = b;return true;}return false;}
constexpr int INF = 1e18;

template<int MOD> struct Fp {
	long long val;
	constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
		if (val < 0) val += MOD;
	}
	constexpr int getmod() { return MOD; }
	constexpr Fp operator - () const noexcept {
		return val ? MOD - val : 0;
	}
	constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
	constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
	constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
	constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
	constexpr Fp& operator += (const Fp& r) noexcept {
		val += r.val;
		if (val >= MOD) val -= MOD;
		return *this;
	}
	constexpr Fp& operator -= (const Fp& r) noexcept {
		val -= r.val;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr Fp& operator *= (const Fp& r) noexcept {
		val = val * r.val % MOD;
		return *this;
	}
	constexpr Fp& operator /= (const Fp& r) noexcept {
		long long a = r.val, b = MOD, u = 1, v = 0;
		while (b) {
			long long t = a / b;
			a -= t * b; swap(a, b);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr bool operator == (const Fp& r) const noexcept {
		return this->val == r.val;
	}
	constexpr bool operator != (const Fp& r) const noexcept {
		return this->val != r.val;
	}
	friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
		return os << x.val;
	}
	friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
		if (n == 0) return 1;
		auto t = modpow(a, n / 2);
		t = t * t;
		if (n & 1) t = t * a;
		return t;
	}
};

// 二項係数ライブラリ
template<class T> struct BiCoef {
	vector<T> fact_, inv_, finv_;
	constexpr BiCoef() {}
	constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
		init(n);
	}
	constexpr void init(int n) noexcept {
		fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
		int MOD = fact_[0].getmod();
		for(int i = 2; i < n; i++){
			fact_[i] = fact_[i-1] * i;
			inv_[i] = -inv_[MOD%i] * (MOD/i);
			finv_[i] = finv_[i-1] * inv_[i];
		}
	}
	constexpr T com(int n, int k) const noexcept {
		if (n < k || n < 0 || k < 0) return 0;
		return fact_[n] * finv_[k] * finv_[n-k];
	}
	constexpr T fact(int n) const noexcept {
		if (n < 0) return 0;
		return fact_[n];
	}
	constexpr T inv(int n) const noexcept {
		if (n < 0) return 0;
		return inv_[n];
	}
	constexpr T finv(int n) const noexcept {
		if (n < 0) return 0;
		return finv_[n];
	}
};

const int MOD = 1000000007;
// const int MOD =
using mint = Fp<MOD>;
BiCoef<mint> bc;
// bc.init(500050);

int gcdExtended(int a, int b, int *x, int *y) {
    if (a == 0) { *x = 0, *y = 1; return b; }
    int x1, y1; int gcd = gcdExtended(b%a, a, &x1, &y1);
    *x = y1 - (b/a) * x1;    *y = x1;
    return gcd;
}
int modInverse(int a) { // not for a = 0
    int x, y;    int g = gcdExtended(a, MOD, &x, &y);
    if (g != 1) return -1;   else return (x%MOD + MOD) % MOD;
}

signed main(){
//	freopen("in.txt", "r", stdin);  freopen("out.txt", "w", stdout);
	int N,K;
	cin >> N >> K;
	bc.init(500050);
	mint ans = 0;
//	if(K > N) {
//		out(bc.com(N, 2*N-1)); return 1; // C(k, n+k-1): xep k bong vao n ro
//	}

	for(int i = 0; i<= min(K, N); ++i) { // co i phong khong nguoi
		mint way = bc.com(N, i); // so cach chon i phong khong nguoi = C(i, n)
		//int m = n - i = so phong phai co nguoi >=1, tong so nguoi = n => sau khi bo di m
		// nguoi thi phai xep n-m nguoi nay vao n-i phong => C(n-m, n-m+n-i-1) = C(i, n-1)
		// C(i, n-1) = ( C(i, n)/n ) * (n-i) suy ra;
		int NI = modInverse(N);
		mint conguoi = bc.com(N, i) * (N-i);
		conguoi = conguoi * NI;
		ans += way * conguoi;
	}

//	FOR(i,max(1ll,N-K),N+1){
//		ans += bc.com(N,i) * bc.com(i + N - i - 1, N - i);
//	}
	out(ans);
}


Measured memory_bytes: 11904