HA32_PiggyBank(12)

#include <iostream>
#include <vector>

class PiggyBankSystem {
private:
    int N;
    std::vector<int> keyPlacement;
    std::vector<bool> visited;
    std::vector<bool> inStack;

public:
    PiggyBankSystem(int n, std::vector<int> keys)
        : N(n), keyPlacement(n + 1), visited(n + 1, false), inStack(n + 1, false) {
        for (int i = 1; i <= n; ++i) {
            keyPlacement[i] = keys[i];
        }
    }

    int findMinPiggyBanksToBreak() {
        int cycleCount = 0;
        for (int i = 1; i <= N; ++i) {
            if (!visited[i]) {
                int j = i;
                std::vector<int> path;
                bool isCycle = false;
                while (!visited[j]) {
                    visited[j] = true;
                    inStack[j] = true;
                    path.push_back(j);
                    j = keyPlacement[j];
                    if (inStack[j]) {
                        // Нашли цикл
                        cycleCount++;
                        break;
                    }
                }
                // Пометим все узлы в пути как не входящие в стек
                for (int node : path) {
                    inStack[node] = false;
                }
            }
        }
        return cycleCount;
    }
};

int main() {
    int N;
    std::cin >> N;
    std::vector<int> keys(N + 1);
    for (int i = 1; i <= N; ++i) {
        std::cin >> keys[i];
    }
    PiggyBankSystem system(N, keys);
    int result = system.findMinPiggyBanksToBreak();
    std::cout << result << std::endl;
    return 0;
}