#!/usr/bin/env python3

# https://cs.stackexchange.com/questions/123381/number-of-connected-induced-subgraph-in-a-tree

import sys
sys.setrecursionlimit(1000000)

BIG = 10**9+7

def dfs(i,vis,A,B,search):
  vis[i] = True
  S[i] = search
  loop = False
  mult = 0
  result = 0
  if i in par: # see if any children
    for j in par[i]:
      if not vis[j]:
        result = dfs(j,vis,A,B,search)
        if result > 0: # backing up from a loop node
          mult = result
        else:
          A[i] = (A[i]+A[j]+B[j])%BIG
          B[i] = (B[i]*(1+B[j]))%BIG

      elif S[j] != search: # incorporate j's A,B values into i
        A[i] = (A[i]+A[j]+B[j])%BIG
        B[i] = (B[i]*(1+B[j]))%BIG
      else: # we're the last node in the loop--this can happen only once
        loop = True
  if loop:
    return B[i]
  else:
    return (B[i]*mult)%BIG

n = int(sys.stdin.readline())
par = {}
for i in range(n):
  x = int(sys.stdin.readline())
  if x-1 in par:
    par[x-1].append(i)
  else:
    par[x-1] = [i]
  
vis = [False for i in range(n)]
A = [0 for i in range(n)]
B = [1 for i in range(n)]
S = [0 for i in range(n)] # search number

ans = 1
search = 0
for i in range(n):
  if vis[i]: continue
  search += 1
  ret = dfs(i,vis,A,B,search)
  if ret > 0:
    ans = (ans*(ret+1))%BIG
print((ans-1+BIG)%BIG)