#include <bits/stdc++.h>
using namespace std;
vector<int> prime_Numbers;
bool primes[1000005];
void prime(int n) {
  for (int i = 2; i <= n; i++) primes[i] = true;
  for (int i = 2; i <= n; i++) {
    if (primes[i] == true) {
      prime_Numbers.push_back(i);
      for (int j = i + i; j <= n; j += i) primes[j] = false;
    }
  }
}
int fib(int n) {
  if (n == 1 || n == 0) return n;
  return fib(n - 1) + fib(n - 2);
}
long long fastpower(int b, int p) {
  if (p == 0) return 1;
  long long term = fastpower(b, p / 2);
  term *= term;
  if (p % 2 != 0) return term *= b;
  return term;
}
long long arr[3005];
int main() {
  int a, b;
  cin >> a >> b;
  if (a == 9 && b == 1)
    cout << "9 10";
  else if (a == b)
    cout << a << 1 << " " << b << 2;
  else if (a + 1 == b)
    cout << a << 9 << " " << b << 0;
  else
    cout << -1;
  return 0;
}
