using System;
using System.Linq;
using System.Numerics;

namespace Sample
{
    class Program
    {
        static void Main(string[] args)
        {
            var arr = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
            var (N, M) = (arr[0], arr[1]);
            var MOD = (long)Math.Pow(10, 9) + 7;
            long ans;
            if (N == M)
            {
                ans = nPk(N, M - 1, MOD);
            }
            else
            {
                ans = (long)(nPk(N, M, MOD) * BigInteger.ModPow((N - M), M, MOD) % MOD);
            }
           
            Console.WriteLine(ans);
        }

        /// <summary>
        /// 順列 (n >= k)
        /// </summary>
        public static long nPk(long n, long k, long mod)
        {
            if (n < k) return 0;
            if (n == k) return 1;

            long x = 1;
            for (long i = 0; i < k; i++)
            {
                x = x * (n - i) % mod;
            }
            return x;
        }
    }
}