Useless use of logical xor in void context at -e line 1.
$VAR1 = [
          1,
          5,
          9,
          13
        ];
$VAR2 = [
          2,
          6,
          10,
          14
        ];
$VAR3 = [
          3,
          7,
          11
        ];
$VAR4 = [
          4,
          8,
          12
        ];