Untitled

import java.util.*;

class IntSet {
    private TreeSet<Integer> ts;
    
    public IntSet(int[] a)
    {
        for(int val: a)
            ts.add(val);
    }
    
    public IntSet union(IntSet other)
    {
        IntSet res = new IntSet(new int[0]);
        res.ts.addAll(this.ts);
        res.ts.addAll(other.ts); 
        return res;
    }
    
    @Override
    public String toString() {
        String result = "";
        for (int x : ts) {
            result += x;
        }
        return result;
    }
}

public class J04021 {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), m = sc.nextInt(), a[] = new int[n], b[] = new int[m];
        for(int i = 0; i<n; i++) a[i] = sc.nextInt();
        for(int i = 0; i<m; i++) b[i] = sc.nextInt();
        IntSet s1 = new IntSet(a);
        IntSet s2 = new IntSet(b);
        IntSet s3 = s1.union(s2);
        System.out.println(s3);
    }
    
}