#include <bits/stdc++.h>
using namespace std;
#define int long long
int n, b[100005], a[200005], tree[200005];
set<int> s;
void update(int u){
while(u <= n * 2 - 1){
tree[u] += 1;
u += (u & -u);
}
}
int get(int u){
int res = 0;
while(u > 0){
res += tree[u];
u -= (u & -u);
}
return res;
}
void solve(){
for(int i = 1; i <= 2 * n - 1; i++) s.insert(i);
s.erase(b[1]);
update(b[1]);
a[1] = b[1];
for(int i = 2; i <= n; i++){
int smaller = get(b[i] - 1);
int bigger = 2 * i - 3 - smaller;
if(s.find(b[i]) == s.end()) bigger--;
else;
if(smaller - bigger == -2){
a[2 * i - 2] = *s.begin();
s.erase(a[2 * i - 2]);
update(a[2 * i - 2]);
a[2 * i - 1] = *s.begin();
s.erase(a[2 * i - 1]);
update(a[2 * i - 1]);
}
else if(smaller - bigger == -1){
a[2 * i - 2] = b[i];
s.erase(a[2 * i - 2]);
update(a[2 * i - 2]);
a[2 * i - 1] = *s.begin();
s.erase(a[2 * i - 1]);
update(a[2 * i - 1]);
}
else if(smaller - bigger == 0){
a[2 * i - 2] = *s.begin();
s.erase(a[2 * i - 2]);
update(a[2 * i - 2]);
a[2 * i - 1] = *s.rbegin();
s.erase(a[2 * i - 1]);
update(a[2 * i - 1]);
}
else if(smaller - bigger == 1){
a[2 * i - 2] = b[i];
s.erase(a[2 * i - 2]);
update(a[2 * i - 2]);
a[2 * i - 1] = *s.rbegin();
s.erase(a[2 * i - 1]);
update(a[2 * i - 1]);
}
else{
a[2 * i - 2] = *s.rbegin();
s.erase(a[2 * i - 2]);
update(a[2 * i - 2]);
a[2 * i - 1] = *s.rbegin();
s.erase(a[2 * i - 1]);
update(a[2 * i - 1]);
}
}
for(int i = 1; i <= 2 * n - 1; i++) cout << a[i] <<" ";
}
signed main(){
//freopen("medians.in", "r", stdin);
//freopen("medians.out", "w", stdout);
ios_base::sync_with_stdio(NULL); cin.tie(nullptr); cout.tie(nullptr);
cin >> n;
for(int i = 1; i <= n; i++) cin >> b[i];
solve();
}
