First column, second column, third column, fourth column First line 1 2 9 10 second line 4 3 8 11 third line 5 6 7 12 fourth line 16 15 14 13

First column, second column, third column, fourth column First line 1 2 9 10 second line 4 3 8 11 third line 5 6 7 12 fourth line 16 15 14 13

I don't understand what it means. How to solve it? What's the problem?