SIZE=10**5+1; MOD=10**9+7 #998244353 #ここを変更する

inv = [0]*SIZE  # inv[j] = j^{-1} mod MOD
fac = [0]*SIZE  # fac[j] = j! mod MOD
finv = [0]*SIZE # finv[j] = (j!)^{-1} mod MOD
fac[0] = fac[1] = 1
finv[0] = finv[1] = 1
for i in range(2,SIZE):
    fac[i] = fac[i-1]*i%MOD
finv[-1] = pow(fac[-1],MOD-2,MOD)
for i in range(SIZE-1,0,-1):
    finv[i-1] = finv[i]*i%MOD
    inv[i] = finv[i]*fac[i-1]%MOD

def choose(n,r): # nCk mod MOD の計算
    if 0 <= r <= n:
        return (fac[n]*finv[r]%MOD)*finv[n-r]%MOD
    else:
        return 0

def perm(n,r): # nPr mod MOD
    if 0 <= r <= n:
        return fac[n]*finv[n-r]%MOD
    else:
        return 0

n = int(input())
*p, = map(int,input().split())
for i in range(n):
    p[i] -= 1

res = []
used = [0]*n
for i in range(n):
    if used[i]: continue
    c = 0
    while used[i]==0:
        used[i] = 1
        i = p[i]
        c += 1
    res.append(c)

#print(res)
ans = fac[n]
for x in res:
    ans *= inv[x]
    ans %= MOD

from collections import Counter
d = Counter(res)
for v in d.values():
    ans *= finv[v]
    ans %= MOD

for x in res:
    if x%2==0: break
else:
    if len(res) >= 2:
        ans *= inv[2]
        ans %= MOD

print(ans)