X - Friends and Gifts

#include <bits/stdc++.h>

using namespace std;

#define fixed(n) fixed << setprecision(n)
#define ceil(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define add_mod(a, b, m) (((a % m) + (b % m)) % m)
#define sub_mod(a, b, m) (((a % m) - (b % m) + m) % m)
#define mul_mod(a, b, m) (((a % m) * (b % m)) % m)
#define all(vec) vec.begin(), vec.end()
#define rall(vec) vec.rbegin(), vec.rend()
#define sz(x) int(x.size())
#define debug(x) cout << #x << ": " << (x) << "\n";
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define Mod  1'000'000'007
#define EPS 1e-9
constexpr int INF = 1 << 30;
constexpr ll LINF = 1LL << 62;
#define PI acos(-1)
template < typename T = int > using Pair = pair < T, T >;
vector < string > RET = {"NO", "YES"};

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x : v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) {
    for (const T &x : v) out << x << ' ';
    return out;
}

void Solve(){
    int n;
    cin >> n;
    set < int > received;
    vector < int > ans(n);
    for(int i = 1; i <= n; i++)
        received.insert(i);
    for(int i = 0, x; i < n && cin >> x; i++){
        if(x > 0)
            received.erase(x);
        ans[i] = x;
    }
    int last_received = -1;
    for(int i = 0; i < n; i++){
        if(ans[i] == 0){
            if(i + 1 == *received.rbegin())
                ans[i] = *received.begin();
            else
                ans[i] = *received.rbegin();
            if(ans[i] == i + 1){
                swap(ans[i], ans[last_received]);
                break;
            }
            received.erase(ans[i]);
            last_received = i;
        }
    }
    cout << ans << '\n';
}

int main(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    int test_cases = 1;
    // cin >> test_cases;
    for(int tc = 1; tc <= test_cases; tc++){
        // cout << "Case #" << tc << ": ";
        Solve();
    }
    return 0;
}