import sys
#sys.setrecursionlimit(10 ** 6)
INF = float('inf')
#10**20,2**63に変えるのもあり
MOD = 10**9 + 7
MOD2 = 998244353
from collections import defaultdict
def ceil(A,B):
    return -(-A//B)
def solve():
    def II(): return int(sys.stdin.readline())
    def LI(): return list(map(int, sys.stdin.readline().split()))
    def LC(): return list(input())
    def IC(): return [int(c) for c in input()]
    def MI(): return map(int, sys.stdin.readline().split())
    N = II()
    P = LI()
    Ans = 0
    for i in range(N):
        if(P[i]!=i+1):
            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)
    return
solve()