#include <iostream>
#include <cmath>
#include <vector>
#include <string>
#include <algorithm>
#include <fstream>
#include <set>
#include <iomanip>
#include <iso646.h>
#include <stdio.h>
#include <map>
#define sync ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define ss second
#define ff first
#define ll long long
#define mp make_pair
#define endl "\n"
#define pb push_back
#define ld long double
#define M_PI 3.14159265358979323846  /* pi */
const double EPS = 0.0000000001;
using namespace std;
const ll INF = 1000000007;

ll binpow(ll a, ll n) {
	ll res = 1;
	while (n) {
		if (n & 1)
		{
			res *= a;
			res %= INF;
			n--;
		}
		else
		{
			a *= a;
			a %= INF;
			n /= 2;
		}
	}
	return res;
}

ll C(ll n, ll k) {
	ll res = 1;
	for (int i = 1; i <= k; ++i)
		res = (res * (n - k + i) % INF*binpow(i, INF - 2))%INF;
	return res;
}

int main()
{
	sync;
	ll n, k;
	cin >> n >> k;
	cout << C(n - 1, n - k)%INF;
	return 0;

}