MOD = 10**9 + 7

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    N = int(data[0])
    A = list(map(int, data[1:N+1]))
    
    from collections import defaultdict
    freq = defaultdict(int)
    for x in A:
        freq[x] += 1
    
    D = list(freq.keys())
    m = len(D)
    
    max_k = m
    f = [0] * (max_k + 1)
    f[0] = 1
    for x in D:
        c = freq[x]
        for k in range(max_k, 0, -1):
            f[k] = (f[k] + f[k-1] * c) % MOD
    
    fact = [1] * (N + 1)
    for i in range(1, N + 1):
        fact[i] = fact[i-1] * i % MOD
    
    ans = 0
    for k in range(0, m + 1):
        sign = 1 if k % 2 == 0 else -1
        term = sign * f[k] * fact[N - k]
        term %= MOD
        ans = (ans + term) % MOD
    
    print(ans % MOD)

if __name__ == "__main__":
    main()