MOD = 998244353

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    N = int(data[0])
    M = int(data[1])
    A = int(data[2])
    B = int(data[3])
    
    low = A * (N - 1)
    high = min(B, M - 1)
    
    if low > high:
        print(0)
        return
    
    # Precompute factorial and inverse factorial up to required size
    max_n = (high - low) + (N - 1) + 2  # T_max + H can be up to high-low + (N-1) which is up to around 4e5
    max_fact = max(max_n, N)  # N! needed
    fact = [1] * (max_fact + 1)
    for i in range(1, max_fact + 1):
        fact[i] = fact[i-1] * i % MOD
    
    inv_fact = [1] * (max_fact + 1)
    inv_fact[max_fact] = pow(fact[max_fact], MOD-2, MOD)
    for i in range(max_fact -1, -1, -1):
        inv_fact[i] = inv_fact[i+1] * (i+1) % MOD
    
    def comb(n, k):
        if n < 0 or k < 0 or n < k:
            return 0
        return fact[n] * inv_fact[k] % MOD * inv_fact[n - k] % MOD
    
    H = N - 1
    T_max = high - low
    a = M - low
    
    n = T_max + H
    comb1 = comb(n, H)
    comb2 = comb(n, H + 1)
    
    sum_val = (a * comb1 - H * comb2) % MOD
    if sum_val < 0:
        sum_val += MOD
    
    ans = sum_val * fact[N] % MOD
    print(ans)
    
if __name__ == '__main__':
    main()