#include <fstream>

using namespace std;
int v[10001];
int main()
{
          ifstream fin ("input");
          ofstream fout ("output");
          int n;
          fin >> n;
          for (int i=1; i<=n; ++i)
            fin >> v[i];
          for (int i=1; i<=n; ++i)
            for (int j=1; j<=n; ++j)
          {
              if (v[i]< v[j])
                fout << v[i] << v[j];
              else fout << v[j] << v[i];
          }
          return 0;
}