#include "bits/stdc++.h" using namespace std; #ifdef _DEBUG #include "dump.hpp" #else #define dump(...) #endif //#define int long long #define rep(i,a,b) for(int i=(a);i<(b);i++) #define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--) #define all(c) begin(c),end(c) const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f; const int MOD = 1'000'000'007; template bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; } signed main() { cin.tie(0); ios::sync_with_stdio(false); int N; cin >> N; vector v(N); rep(i, 0, N) { cin >> v[i]; } priority_queue, greater> pq; rep(i, 0, N)pq.push(v[i]); string ans = ""; while (pq.size()) { string t = pq.top(); pq.pop(); ans += t.front(); t = t.substr(1); if (t.size()) pq.push(t); } cout << ans << endl; return 0; }