class UnionFind:
    def __init__(self,n):
        self.n = n
        self.parent_size = [-1]*n
 
    def leader(self,a):
        if self.parent_size[a] < 0:
            return a
        self.parent_size[a] = self.leader(self.parent_size[a])
        return self.parent_size[a]
 
    def merge(self,a,b):
        x, y = self.leader(a), self.leader(b)
        if x == y:
            return 
        if abs(self.parent_size[x]) < abs(self.parent_size[y]):
            x, y = y, x
        self.parent_size[x] += self.parent_size[y]
        self.parent_size[y] = x
        return 
 
    def same(self,a,b):
        return self.leader(a) == self.leader(b)
 
    def size(self,a):
        return abs(self.parent_size[self.leader(a)])
 
    def groups(self):
        result = [[] for _ in range(self.n)]
        for i in range(self.n):
            result[self.leader(i)].append(i)
        return [r for r in result if r != []]

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

UF = UnionFind(N)
for i, p in enumerate(P):
    UF.merge(i, p-1)

ans = 0
for i in range(N):
    if UF.leader(i) == i:
        ans += UF.size(i)-1

print(ans)