class UF:
    def __init__(self,n):
        self.p = [-1]*n
    def f(self,x):
        if self.p[x]<0: return x
        else: self.p[x] = self.f(self.p[x]); return self.p[x]
    def u(self,x,y):
        x = self.f(x); y = self.f(y)
        if x==y: return
        if -self.p[x]<-self.p[y]: x,y = y,x
        self.p[x] += self.p[y]; self.p[y] = x
n = int(input()); uf = UF(n); s = set()
for i,v in enumerate(map(int,input().split())): uf.u(i,v-1)
for i in range(n): s.add(uf.f(i))
print(n-len(s))