C:\Users\Fred\Desktop\pm>perl dis1.pl
Argument "CA" isn't numeric in subtraction (-) at dis1.pl line 38, <IN> line 4 (
#1)
    (W numeric) The indicated string was fed as an argument to an operator
    that expected a numeric value instead.  If you're fortunate the message
    will identify which operator was so unfortunate.

Argument "N" isn't numeric in subtraction (-) at dis1.pl line 38, <IN> line 4 (#
1)
Argument "MSE" isn't numeric in subtraction (-) at dis1.pl line 38, <IN> line 4
(#1)
Argument "C" isn't numeric in subtraction (-) at dis1.pl line 38, <IN> line 4 (#
1)
Argument "O" isn't numeric in subtraction (-) at dis1.pl line 38, <IN> line 4 (#
1)
Done.