#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  int a[n], b[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 + n);
  if (a[0] == 1 && b[0] == 1)
    cout << "1";
  else
    cout << min(a[0], b[0]) * 10 + (max(a[0], b[0]));
  return 0;
}
