#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
template<typename Type>
class FenwickTree {
private:
std::vector<Type> bit;
public:
FenwickTree(int n = 0, Type v = 0) {
Assign(n, v);
}
void Assign(int n = 0, int v = 0) {
bit.assign(n+1, 0);
for (int i = 1; i <= n; i++) {
bit[i] += v;
if (i+(i&-i)<=n) {
bit[i+(i&-i)] += bit[i];
}
}
}
void Add(int pos, Type val) {
while (pos < bit.size()) {
bit[pos] += val;
pos += pos&-pos;
}
}
Type Query(int pos) {
Type ret = 0;
while (pos > 0) {
ret += bit[pos];
pos ^= pos&-pos;
}
return ret;
}
Type Query(int l, int r) {
return Query(r) - Query(l-1);
}
int BinaryLifting(Type val) {
int ret = 0;
for (int step = 1<<18; step; step >>= 1) {
if (ret+step < bit.size() && val - bit[ret+step] > 0) {
val -= bit[ret+step];
ret += step;
}
}
return ret+1;
}
};
int x;
int arr[100005];
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(NULL);
std::cout.tie(NULL);
std::cin >> x;
FenwickTree<int> fnwk_remaining(2*x-1, 1);
FenwickTree<int> fnwk_deleted(2*x-1, 0);
for (int i = 1, tmp; i <= x; i++) {
std::cin >> tmp;
//std::cout << tmp << " " << fnwk.Query(tmp-1) << " " << fnwk.Query(tmp+1, 2*x-1) << "\n";
#if 1
if (i==1) {
std::cout << tmp << " ";
fnwk_remaining.Add(tmp, -1);
fnwk_deleted.Add(tmp, 1);
continue;
}
int less = fnwk_deleted.Query(tmp-1);
int greater = fnwk_deleted.Query(tmp+1, 2*x-1);
if (less == greater) {
int a = fnwk_remaining.BinaryLifting(1);
int b = fnwk_remaining.BinaryLifting(fnwk_remaining.Query(1,2*x-1));
std::cout << a << " " << b << " ";
fnwk_remaining.Add(a, -1);
fnwk_remaining.Add(b, -1);
fnwk_deleted.Add(a, 1);
fnwk_deleted.Add(b, 1);
}
else if (less == greater-1) {
int a = fnwk_remaining.BinaryLifting(1);
int b = tmp;
std::cout << a << " " << b << " ";
fnwk_remaining.Add(a, -1);
fnwk_remaining.Add(b, -1);
fnwk_deleted.Add(a, 1);
fnwk_deleted.Add(b, 1);
}
else if (less == greater+1) {
int a = tmp;
int b = fnwk_remaining.BinaryLifting(fnwk_remaining.Query(1,2*x-1));
std::cout << a << " " << b << " ";
fnwk_remaining.Add(a, -1);
fnwk_remaining.Add(b, -1);
fnwk_deleted.Add(a, 1);
fnwk_deleted.Add(b, 1);
}
#endif
}
std::cout << "\n";
}
