#include <bits/stdc++.h>
using namespace std;
int n, m, a[10], b[10];
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;
      }
    }
  }
  if (a[0] > b[0])
    cout << b[0] * 10 + a[0] << endl;
  else
    cout << a[0] * 10 + b[0] << endl;
  return 0;
}
