#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  if (a == b) {
    cout << a << 1 << " " << b << 2;
  } else if (a + 1 == b) {
    cout << a << " " << b;
  } else if (a == 9 && b == 1)
    cout << "9 10";
  else
    cout << -1;
}
