## https://yukicoder.me/problems/no/3078

MOD = 998244353


class CombinationCalculator:
    """
    modを考慮したPermutation, Combinationを計算するためのクラス
    """    
    def __init__(self, size, mod):
        self.mod = mod
        self.factorial = [0] * (size + 1)
        self.factorial[0] = 1
        for i in range(1, size + 1):
            self.factorial[i] = (i * self.factorial[i - 1]) % self.mod
        
        self.inv_factorial = [0] * (size + 1)
        self.inv_factorial[size] = pow(self.factorial[size], self.mod - 2, self.mod)

        for i in reversed(range(size)):
            self.inv_factorial[i] = ((i + 1) * self.inv_factorial[i + 1]) % self.mod

    def calc_combination(self, n, r):
        if n < 0 or n < r or r < 0:
            return 0

        if r == 0 or n == r:
            return 1
        
        ans = self.inv_factorial[n - r] * self.inv_factorial[r]
        ans %= self.mod
        ans *= self.factorial[n]
        ans %= self.mod
        return ans
    
    def calc_permutation(self, n, r):
        if n < 0 or n < r:
            return 0

        ans = self.inv_factorial[n - r]
        ans *= self.factorial[n]
        ans %= self.mod
        return ans
        

def main():
    N, M, A, B = map(int, input().split())

    if A * (N - 1) > B:
        print(0)
        return
    
    combi = CombinationCalculator(M + N, MOD)
    answer = 0
    for n in range(A * (N - 1), B + 1):
        m1 = n - (A * (N - 1))
        m2 = N - 2
        x = combi.calc_combination(m1 + m2, m2)
        x *= combi.factorial[N]
        x %= MOD


        x *= (M - (1 + n) + 1)
        x %= MOD

        answer += x
        answer %= MOD
    
    print(answer)
    


    


if __name__ == "__main__":
    main()