BAEKJOON 11401

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	static long N, R;
	static long MOD = 1_000_000_007;

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		N = Long.parseLong(st.nextToken());
		R = Long.parseLong(st.nextToken());
		System.out.println((fak(N) * pow(fak(R) * fak(N - R) % MOD, MOD - 2)%MOD)%MOD);
	}

	private static long pow(long base, long expo) {
		long num = 1;
		while (expo > 0) {
			if (expo % 2 == 1) {
				num *= base;
				num %= MOD;
			}
			expo /= 2;
			base *= base;
			base %= MOD;
		}
		return num;
	}

	private static long fak(long n) {
		long num = 1;
		while (n > 1) {
			num = num * n--;
			num = num % MOD;
		}
		return num;
	}
}