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

ans = 0
for i in range(N):
    if P[i] == i+1:
        continue
    for j in range(i+1, N):
        if P[j] == i+1:
            P[i], P[j] = P[j], P[i]
            ans += 1
            break
print(ans)