N = int(input())
A = list(map(int, input().split()))

dic = dict()
for i, a in enumerate(A):
    dic[a] = i

cnt = 0
for i in range(N):
    if A[i] == i + 1:
        continue
    idx2 = dic[i + 1]
    # print(idx2)
    A[i], A[idx2] = A[idx2], A[i]
    dic[A[i]] = i
    dic[A[idx2]] = idx2
    cnt += 1

print(cnt)