MOD = 998244353

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    M = int(data[0])
    N = int(data[1])
    A = list(map(int, data[2:2+N]))
    
    from collections import defaultdict
    freq = defaultdict(int)
    for a in A:
        freq[a] += 1
    Cs = list(freq.values())
    K_min = max(Cs) if Cs else 0
    
    if K_min == 0:
        print(0)
        return
    
    max_t = N
    size = max_t + 2
    
    fact = [1] * (size)
    inv_fact = [1] * (size)
    for i in range(1, size):
        fact[i] = fact[i-1] * i % MOD
    inv_fact[size-1] = pow(fact[size-1], MOD-2, MOD)
    for i in range(size-2, -1, -1):
        inv_fact[i] = inv_fact[i+1] * (i+1) % MOD
    
    def comb(n, k):
        if n < 0 or k < 0 or k > n:
            return 0
        return fact[n] * inv_fact[k] % MOD * inv_fact[n - k] % MOD
    
    def P(t, c):
        if t < c:
            return 0
        return fact[t] * inv_fact[t - c] % MOD
    
    f = [0] * (max_t + 2)
    for t in range(K_min, max_t + 1):
        prod = 1
        for c in Cs:
            prod = prod * P(t, c) % MOD
        f[t] = prod
    
    total = 0
    for K in range(K_min, N + 1):
        res = 0
        for d in range(0, K - K_min + 1):
            t = K - d
            if t < K_min:
                continue
            term = f[t] * pow(-1, d, MOD) % MOD
            term = term * comb(K, d) % MOD
            res = (res + term) % MOD
        total = (total + res) % MOD
    
    print(total % MOD)

if __name__ == '__main__':
    main()