pb 43

#include <iostream>
using namespace std;

int main()
{
    int n, v[1000];
    cin >> n;
    for (int i = 0; i < n;i++)
    {
        int x;
        cin >> x;
        while (x > 9)
            x /= 10;
        v[i] = x;
    }

    for (int i = 0; i < n - 1; i++)
        for (int j = i + 1; j < n; j++)
        if (v[i] > v[j])
    {
        int aux = v[i];
        v[i] = v[j];
        v[j] = aux;
    }
    for (int i = 0; i < n; i++)
        cout << v[i];
    return 0;
}