#include <bits/stdc++.h>
using namespace std;
int n, m, a[9], b[9];
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < m; i++) cin >> b[i];
  sort(a, a + n);
  sort(b, b + m);
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++)
      if (a[i] == b[j]) {
        cout << a[i] << endl;
        return 0;
      }
  cout << min(a[0], b[0]) << max(a[0], b[0]) << endl;
}
