#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int INF = (int)1e9;
const long long LINF = (long long)1e18;
const long double PI = acos((long double)-1);
const long double EPS = 1e-9;
long long gcd(long long a, long long b) {
  long long r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long fpow(long long n, long long k, int p = MOD) {
  long long r = 1;
  for (; k; k >>= 1) {
    if (k & 1) r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T>
void setmin(T& a, T val) {
  if (a > val) a = val;
}
template <class T>
void setmax(T& a, T val) {
  if (a < val) a = val;
}
void addmod(int& a, int val, int p = MOD) {
  if ((a = (a + val)) >= p) a -= p;
}
void submod(int& a, int val, int p = MOD) {
  if ((a = (a - val)) < 0) a += p;
}
int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }
int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
int mark[2000005];
int main() {
  int n, m;
  cin >> n >> m;
  int a[n], b[m];
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    mark[a[i]]++;
  }
  for (int i = 0; i < m; ++i) {
    cin >> b[i];
    mark[b[i]]++;
  }
  sort(a, a + n);
  sort(b, b + m);
  int p = INT_MAX;
  int mn = min(a[0], b[0]);
  int mx = max(a[0], b[0]);
  for (int i = 0; i < n; i++) {
    if (mark[a[0]] == 2) {
      p = a[0];
      break;
    }
  }
  for (int i = 0; i < m; i++) {
    if (mark[b[0]] == 2) {
      p = min(p, b[0]);
      break;
    }
  }
  if (p != INT_MAX) {
    cout << p << endl;
  } else
    cout << mn << mx << endl;
}
