using static System.Math;
using System;

public class Hello
{
    public static int MOD = 998244353;
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var x = int.Parse(line[0]);
        var y = int.Parse(line[1]);
        var z = int.Parse(line[2]);
        var w = int.Parse(line[3]);
        if (w == 0) getAns(x, y, z);
        else getAns(y, x, w);
    }
    static void getAns(int x, int y, int z)
    {
        var max = x + y + z;
        var md = new Modulo(max);
        long ans = md.Fac(x - z + y - 1);
        var t = md.Ncr(x, x - z);
        ans *= t;
        ans %= MOD;
        ans *= y;
        ans %= MOD;
        Console.WriteLine(ans);
    }
    class Modulo
    {
        private int MOD = Hello.MOD;
        private readonly int[] m_facs;
        public int Mul(int a, int b) => (int)(BigMul(a, b) % MOD);
        public Modulo(int n)
        {
            m_facs = new int[n + 1];
            m_facs[0] = 1;
            for (int i = 1; i <= n; ++i)
                m_facs[i] = Mul(m_facs[i - 1], i);
        }
        public int Fac(int n) => m_facs[n];
        public int Pow(int a, int m)
        {
            switch (m)
            {
                case 0:
                    return 1;
                case 1:
                    return a;
                default:
                    int p1 = Pow(a, m / 2);
                    int p2 = Mul(p1, p1);
                    return ((m % 2) == 0) ? p2 : Mul(p2, a);
            }
        }
        public int Div(int a, int b) => Mul(a, Pow(b, MOD - 2));
        public int Ncr(int n, int r)
        {
            if (n < r) return 0;
            if (n == r) return 1;
            int res = Fac(n);
            res = Div(res, Fac(r));
            res = Div(res, Fac(n - r));
            return res;
        }
    }
}