#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  if (a == b)
    cout << a * 10 << " " << b * 10 + 1;
  else if (a == b - 1)
    cout << a << " " << b;
  else if (a == 9 && b == 1)
    cout << 9 << " " << 10;
  else
    cout << -1;
  return 0;
}
