Submission #891184

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Source Code Expand

// In the name of God

#include <iostream>
#include <algorithm>
#include <fstream>
#include <vector>
#include <deque>
#include <assert.h>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <stdio.h>
#include <string.h>
#include <utility>
#include <math.h>
#include <bitset>
#include <iomanip>

using namespace std;

#define rep(i, n) for (int i = 0, _n = (int)(n); i < _n; ++i)
const int N = (int) 1e6 + 6, mod = (int) 0;
int a[N];
int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n;
    cin >> n;
    for (int i = 0; i < n; ++i)
        cin >> a[i], a[i]--;
    int res = 0;
    for (int i = 0; i < n; ++i)
        res += (a[a[i]] == i);
    res >>= 1;
    cout << res << endl;

}

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