import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.StringTokenizer;
import java.io.Writer;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author zodiacLeo
 */
public class Main
{
    public static void main(String[] args)
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastScanner in = new FastScanner(inputStream);
        FastPrinter out = new FastPrinter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA
    {
        public void solve(int testNumber, FastScanner in, FastPrinter out)
        {
            int n = in.nextInt();
            int m = in.nextInt();
            int A = 10;
            int B = 10;
            int[] a = new int[n];
            int[] b = new int[m];
            for (int i = 0; i < n; i++)
            {
                a[i] = in.nextInt();
                A = Math.min(A, a[i]);
            }

            for (int i = 0; i < m; i++)
            {
                b[i] = in.nextInt();
                B = Math.min(B, b[i]);
            }

            int min = Integer.MAX_VALUE;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < m; j++)
                {
                    if (a[i] == b[j])
                    {
                        min = Math.min(min, b[j]);
                    }
                }
            }
            out.println(Math.min(A * 10 + B, Math.min(B * 10 + A, min)));
        }

    }

    static class FastScanner
    {
        public BufferedReader br;
        public StringTokenizer st;

        public FastScanner(InputStream is)
        {
            br = new BufferedReader(new InputStreamReader(is));
        }

        public FastScanner(File f)
        {
            try
            {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e)
            {
                e.printStackTrace();
            }
        }

        public String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                String s = null;
                try
                {
                    s = br.readLine();
                } catch (IOException e)
                {
                    e.printStackTrace();
                }
                if (s == null)
                    return null;
                st = new StringTokenizer(s);
            }
            return st.nextToken();
        }

        public int nextInt()
        {
            return Integer.parseInt(next());
        }

    }

    static class FastPrinter extends PrintWriter
    {
        public FastPrinter(OutputStream out)
        {
            super(out);
        }

        public FastPrinter(Writer out)
        {
            super(out);
        }

    }
}

