N = int(input())
P = list(map(int,input().split()))
A = [0]*(N+1)
B = [False]*(N+1)
for i in range(N):
	A[i+1] = P[i]
	B[P[i]] = True
ans = 0
C = [False]*(N+1)
for i in range(1,N+1):
	if(A[A[i]] != i and A[A[i]] != 0 and B[i] == False):
		C[A[A[i]]] = True
print(sum(C))