#include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     int n, d;     cin >> n;     unordered_set<int> s;     int mx = n;     int c = 0;     for (int i = 0; i < n; i++) {       cin >> d;       if (d == mx) {         for (int i = 0; i < c; i++) cout <<   n ;         cout << mx;         c = 0;         int k = mx - 1;         while (s.find(k) != s.end()) {           cout <<     << k;           s.erase(k);           k--;         }         cout <<   n ;         mx = k;       } else {         s.insert(d);         c++;       }     }     return 0;   }   