class Combi():
    def __init__(self, N, mod):
        self.power = [1 for _ in range(N+1)]
        self.rev = [1 for _ in range(N+1)]
        self.mod = mod
        for i in range(2, N+1):
            self.power[i] = (self.power[i-1]*i) % self.mod
        self.rev[N] = pow(self.power[N], self.mod-2, self.mod)
        for j in range(N, 0, -1):
            self.rev[j-1] = (self.rev[j]*j) % self.mod

    def com(self, K, R):
        if K < R:
            return 0
        else:
            return ((self.power[K])*(self.rev[K-R])*(self.rev[R])) % self.mod

    def pom(self, K, R):
        if K < R:
            return 0
        else:
            return (self.power[K])*(self.rev[K-R]) % self.mod


def main():
    mod = 998244353
    N, M, A, B = map(int, input().split())
    Com = Combi(3*10**5, mod)
    ans = 0
    for k in range(A, B+1):
        if k >= A*(N-1):
            ans += Com.com(k-(A-1)*(N-1)-1, N-2)*(M-k)
    for i in range(1, N+1):
        ans *= i
        ans %= mod
    print(ans)
    return


if __name__ == "__main__":
    main()