#include <iostream>
#include <string>
using namespace std;
int main() {
int x1, x2, i, Max=0, Min=9;
cin >> x1 >> x2;
int a[x1], b[x2];
for (i=1; i<=x1; i++) {
cin >> a[i];
if (a[i] > Max) {
Max = a[i];
}
if (a[i] < Min) {
Min = a[i];
}
}
for (i=1; i<=x2; i++) {
cin >> b[i];
if (b[i] > Max) {
Max = b[i];
}
if (b[i] < Min) {
Min = b[i];
}
}
if (Min == 0) {
cout << to_string(Max) + to_string(Min);
} else {
cout << to_string(Min) + to_string(Max);
}
return 0;
}
