from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

N = int(input())
P = list(map(int,input().split()))
P = [i-1 for i in P]
ans = 0
for i in range(N):
    if P[i]!=i:
        for j in range(i+1,N):
            if P[j]==i:
                P[i],P[j] = P[j],P[i]
                break
        ans += 1
print(ans)