import sys
input = sys.stdin.readline


def main():
    _ = int(input())
    P = list(map(int, input().split()))
    idx = dict()
    for i, p in enumerate(P):
        idx[p] = i
    ans = 0
    for i, p in enumerate(P):
        if i + 1 == p:
            continue
        q = i + 1
        j = idx[q]
        P[i], P[j] = q, p
        idx[p], idx[q] = j, i
        ans += 1
    print(ans)


main()