import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.io.*;
import java.util.Arrays;
 
 /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
 
///**
 //*
  //* @author aman_robotics
// */
public class like_cs01
{
    
    public static void main(String [] args)throws IOException
    {
        FastReader in=new FastReader(System.in);
        int a=in.nextInt();
        int b=in.nextInt();
        int a1[]=new int[a];
        int b1[]=new int[b];
        for(int i=0;i<a;i++)
            a1[i]=in.nextInt();
        for(int i=0;i<b;i++)
            b1[i]=in.nextInt();
        Arrays.sort(a1);
        Arrays.sort(b1);
        int x=Math.min(a1.length,b1.length);
        //int flag=0;
        if(x==a1.length){
            int flag1=0;
            for(int i=0;i<a1.length;i++){
                int flag=0;
                for(int j=0;j<b1.length;j++){
                    if(a1[i]==b1[j]){
                        System.out.println(a1[i]);
                        flag=1;
                        flag1=1;
                        break;
                    }
                }
                if(flag==1)
                    break;
            }
            if(flag1==0){
                System.out.print(Math.min(a1[0],b1[0]));
                System.out.print(Math.max(a1[0],b1[0]));
            }
        }
        else{
            int flag1=0;
            for(int i=0;i<b1.length;i++){
                int flag=0;
                for(int j=0;j<a1.length;j++){
                    if(b1[i]==a1[j]){
                        System.out.println(a1[j]);
                        flag=1;
                        flag1=1;
                        break;
                    }
                }
                if(flag==1)
                    break;
            }
            if(flag1==0){
                System.out.print(Math.min(a1[0],b1[0]));
                System.out.print(Math.max(a1[0],b1[0]));
            }
        }
    }


        
    static class FastReader{
 
        byte[] buf = new byte[2048];
        int index, total;
        InputStream in;
 
        FastReader(InputStream is) {
            in = is;
        }
 
        int scan() throws IOException {
            if (index >= total) {
                index = 0;
                total = in.read(buf);
                if (total <= 0) {
                    return -1;
                }
            }
            return buf[index++];
        }
 
        String next() throws IOException {
            int c;
            for (c = scan(); c <= 32; c = scan());
            StringBuilder sb = new StringBuilder();
            for (; c > 32; c = scan()) {
                sb.append((char) c);
            }
            return sb.toString();
        }
 
        int nextInt() throws IOException {
            int c, val = 0;
            for (c = scan(); c <= 32; c = scan());
            boolean neg = c == '-';
            if (c == '-' || c == '+') {
                c = scan();
            }
            for (; c >= '0' && c <= '9'; c = scan()) {
                val = (val << 3) + (val << 1) + (c & 15);
            }
            return neg ? -val : val;
        }
 
        long nextLong() throws IOException {
            int c;
            long val = 0;
            for (c = scan(); c <= 32; c = scan());
            boolean neg = c == '-';
            if (c == '-' || c == '+') {
                c = scan();
            }
            for (; c >= '0' && c <= '9'; c = scan()) {
                val = (val << 3) + (val << 1) + (c & 15);
            }
            return neg ? -val : val;
        }
    }
}
 
