using System.Numerics;
using System;

public class Hello
{
    public static int MOD = 1000000007;
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var n = long.Parse(line[0]);
        var k = long.Parse(line[1]);
        getAns(n, k);
    }
    static void getAns(long n, long k)
    {
        var ans = BigInteger.ModPow(n, k, MOD) - BigInteger.ModPow(n - 1, k, MOD);
        if (ans < 0) ans += MOD;
        ans *= n;
        ans %= MOD;
        Console.WriteLine(ans);
    }
}