from collections import Counter

N=int(input())
A=[int(input()) for i in range(N)]
C=Counter(A)

mod=10**9+7
FACT=[1]
for i in range(1,2*10**5+1):
    FACT.append(FACT[-1]*i%mod)

DP=[0]*(N+1)
DP[0]=1

for v in C.values():
    for i in range(N-1,-1,-1):
        DP[i+1]+=DP[i]*v
        DP[i+1]%=mod
        

ANS=0

for i in range(N+1):
    x=FACT[N-i]

    if i%2==0:
        ANS+=x*DP[i]
    else:
        ANS-=x*DP[i]

    ANS%=mod

print(ANS)