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=a1[0];
        int y=b1[0];
        if(x==y)
            System.out.println(x);
        else{
            System.out.print(Math.min(x,y));
            System.out.print(Math.max(x,y));
        }
    }


        
    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;
        }
    }
}
 
