#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  int a, b;
  cin >> a >> b;
  if (a + 1 == b) {
    cout << a << " " << b << endl;
  } else if (a == b) {
    cout << a << "0 " << b << "1" << endl;
  } else if (a == 9 && b == 1) {
    cout << a << " " << b << "0" << endl;
  } else {
    cout << -1 << endl;
  }
  return 0;
}
