N = int(input())
P = [0] + list(map(int, input().split()))

in_deg = [0]*(N+1)
for x in range(N+1):
   in_deg[P[x]] += 1
Q = [x for x in range(1, N+1) if in_deg[x] == 0]

dp = [0]*(N+1)
for v in Q:
   dp[P[P[v]]] |= 1

print(sum(dp[1:]))