哈哈哈
#include <cstdio>
#include <algorithm>
#include <iostream>
using namespace std;
const int N = 10010;
int bot[N];
int n;
int main()
{
scanf("%d",&n);
for(int i=1; i<=n; i++) scanf("%d",&bot[i]);
int cnt=0;
for(int i=1; i<=n; i++)
{
while(bot[i]!=i)
{
int tmp1=bot[bot[i]];
int tmp2=bot[i];
bot[i] = tmp1;
bot[tmp2] = tmp2;
cnt++;
}
}
cout << cnt << endl;
}