import java.util.*;
import java.lang.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Set<Integer> set = new TreeSet<>();
        int m = sc.nextInt();
        // int[] arr1 = new int[m];
        for(int i=0; i<m; i++){
            // arr1[i] = sc.nextInt();
            set.add(sc.nextInt());
        }
        int n = sc.nextInt();
        // int[] arr2 = new int[n];
        for(int i=0; i<n; i++){
            // arr2[i] = sc.nextInt();
            set.add(sc.nextInt());
        }
        StringBuffer sb = new StringBuffer();
        for(Integer i: set){
            sb.append(i);
        }
        System.out.println(sb.toString());
    }
}