#include <bits/stdc++.h>
using namespace std;
int main() {
  int m, n, a[10], b[10], ans2;
  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);
  int mi = min(a[0], b[0]);
  int mx = max(a[0], b[0]);
  int ans = mi * 10 + mx;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (a[i] == b[j]) ans = min(ans, a[i]);
    }
  }
  cout << ans << endl;
  return 0;
}
