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)