I noticed that some accepted solutions to this problem (XORGM) fail on a certain test case

1

2

3 13

10 4

The output should (as I understand the question to be) be 4 10 since 3 xor 4 == 13 xor 10 == 7

But some of the accepted solutions give -1

Did I understand the question wrong or is my concern valid? Is there any other way I should raise awareness about this if my concern *is* valid?