n = int(input())
A = [int(input()) for _ in range(n)]

MOD = 10**9 + 7

cnt = [0] * 5000  # Since A_i <= 4999
for a in A:
    cnt[a] += 1

# Collect all values v where cnt[v] > 0
vs = [v for v in range(5000) if cnt[v] > 0]

# Precompute factorials modulo MOD
fact = [1] * (n + 1)
for i in range(1, n + 1):
    fact[i] = fact[i-1] * i % MOD

# Initialize dynamic programming array
dp = [0] * (n + 1)
dp[0] = 1

# Process each value v with cnt[v] > 0
for v in vs:
    current_cnt = cnt[v]
    for k in range(n - 1, -1, -1):
        if dp[k]:
            dp[k+1] = (dp[k+1] + dp[k] * current_cnt) % MOD

ans = 0
for k in range(n + 1):
    ways = dp[k] * fact[n - k] % MOD
    if k % 2 == 1:
        ways = (-ways) % MOD
    ans = (ans + ways) % MOD

print(ans % MOD)