using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using static System.Math;

public static class P
{
    public static void Main()
    {
        var nm = Console.ReadLine().Split().Select(int.Parse).ToArray();
        var n = nm[0];
        var m = nm[1];
        ModInt res = 0;
        for (int match = 0; match <= n; match++)
        {
            var matchPlaceComb = Factorial(n) / Factorial(match) / Factorial(n - match);
            var matchColorComb = Factorial(m) / Factorial(m - match);

            var remainPlace = n - match;
            var remainColor = m - match;

            var remainPerm = Factorial(remainColor) / Factorial(remainColor - remainPlace);

            var perm = matchColorComb * matchPlaceComb * remainPerm * remainPerm;

            if (match % 2 == 0) res += perm;
            else res -= perm;
        }
        Console.WriteLine(res);
    }

    static List<ModInt> factorialMemo = new List<ModInt>() { 1 };
    static ModInt Factorial(int x)
    {
        for (int i = factorialMemo.Count; i <= x; i++) factorialMemo.Add(factorialMemo.Last() * i);
        return factorialMemo[x];
    }
}

struct ModInt
{
    public const int Mod = 1000000007;
    const long POSITIVIZER = ((long)Mod) << 31;
    long Data;
    public ModInt(long data) { if ((Data = data % Mod) < 0) Data += Mod; }
    public static implicit operator long(ModInt modInt) => modInt.Data;
    public static implicit operator ModInt(long val) => new ModInt(val);
    public static ModInt operator +(ModInt a, int b) => new ModInt() { Data = (a.Data + b + POSITIVIZER) % Mod };
    public static ModInt operator +(ModInt a, long b) => new ModInt(a.Data + b);
    public static ModInt operator +(ModInt a, ModInt b) { long res = a.Data + b.Data; return new ModInt() { Data = res >= Mod ? res - Mod : res }; }
    public static ModInt operator -(ModInt a, int b) => new ModInt() { Data = (a.Data - b + POSITIVIZER) % Mod };
    public static ModInt operator -(ModInt a, long b) => new ModInt(a.Data - b);
    public static ModInt operator -(ModInt a, ModInt b) { long res = a.Data - b.Data; return new ModInt() { Data = res < 0 ? res + Mod : res }; }
    public static ModInt operator *(ModInt a, int b) => new ModInt(a.Data * b);
    public static ModInt operator *(ModInt a, long b) => a * new ModInt(b);
    public static ModInt operator *(ModInt a, ModInt b) => new ModInt() { Data = a.Data * b.Data % Mod };
    public static ModInt operator /(ModInt a, ModInt b) => new ModInt() { Data = a.Data * GetInverse(b) % Mod };
    public static bool operator ==(ModInt a, ModInt b) => a.Data == b.Data;
    public static bool operator !=(ModInt a, ModInt b) => a.Data != b.Data;
    public override string ToString() => Data.ToString();
    public override bool Equals(object obj) => (ModInt)obj == this;
    public override int GetHashCode() => (int)Data;
    static long GetInverse(long a)
    {
        long div, p = Mod, x1 = 1, y1 = 0, x2 = 0, y2 = 1;
        while (true)
        {
            if (p == 1) return x2 + Mod; div = a / p; x1 -= x2 * div; y1 -= y2 * div; a %= p;
            if (a == 1) return x1 + Mod; div = p / a; x2 -= x1 * div; y2 -= y1 * div; p %= a;
        }
    }
}


Measured memory_bytes: 36520