#include <stdio.h>
int main()
{
int a, b, A, B;
scanf_s("%d %d", &a, &b);
A = a + b;
B = a - b;
if (A < 0 || B < 0)
{
printf("-1");
}
else
{
if (A % 2 == 0 && B % 2 == 0)
{
printf("%d %d", A / 2, B / 2);
}
else
{
printf("-1");
}
}
return 0;
}