#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  if (a + 1 == b) {
    cout << a << " " << b;
  } else if (a == b) {
    cout << a * 10 << " " << b * 10 + 1;
  } else if (a == 9 && b == 1) {
    cout << 99 << " " << 100;
  } else {
    cout << -1;
  }
}
