# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
template<class T> bool is_sqare(T a) { if(floor(sqrt(a)) * floor(sqrt(a)) == a){ return true; }return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        (wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((ll)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
# define exists(c, e)         ((c).find(e) != (c).end())
#ifdef LOCAL
#  include "_debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

struct INIT{
	INIT(){
		std::ios::sync_with_stdio(false);
		std::cin.tie(0);
		cout << fixed << setprecision(20);
	}
}INIT;

void solve(){
	int n;
	cin >> n;
	vector<int> p(n);
	for(auto &x : p)cin >> x, x--;
	vector<int> rp(n);
	rep(i, n)rp[p[i]] = i;
	
	vector<int> nxt(n);
	rep(i, n-1)nxt[i] = i+1;
	
	vector<int> ans;
	int cur_num = 0;
	set<int> st;
	
	debug(p, rp, nxt);
	
	while(cur_num < n){
		while(st.count(cur_num))cur_num++;
		if(cur_num >= n)break;
		if(rp[cur_num] == n-1)cur_num++;
		if(cur_num >= n)break;
		ans.pb(cur_num);
		st.insert(cur_num);
		debug(cur_num);

		ans.pb(p[nxt[rp[cur_num]]]);
		st.insert(p[nxt[rp[cur_num]]]);
		if(rp[cur_num] != 0)nxt[rp[cur_num]-1] = nxt[nxt[rp[cur_num]]];
	}
	rep(i, n){
		cout << ans[i]+1 << " \n"[i == n-1];
	}
}

int main(){
    int t = 1;
    //cin >> t;
    while(t--)solve();
}