Hello Monks. Currently, I am making this program that pretty much serves as a study guide for my math class. Unit 6 has to do with quadrilaterals, so I made another script aside from Unit6.pl called CMQIA.pl that runs the "Casio-Maxim Quadrilateral Identification Algorithm" (don't ask). I made it so that if you type "quit" into the script, it'll go back to Unit6.pl. I used:  if($choice !~ /ready/i) {require "Unit6.pl";} Since require LABEL; runs the program, I thought it would work. However, since Unit6.pl has  if($Choice =~ /crazy maxim/i) {require "CMQIA.pl";} something really weird happens now. If I run Unit6.pl and I type crazy maxim, it goes to CMQIA.pl. Then, if I type quit in CMQIA.pl, it goes back to Unit6.pl. Then, if I go to CMQIA.pl from there again, it gives me:  Can't exec "Unit6.pl": No such file or directory at CMQIA.pl line 12, <STDIN> line 3. I've tried a bunch of other things in conjunction with the original code from CMQIA.pl, but nothing ever really works. Any solutions? This is the full code. Unit6.pl

#!/usr/bin/perl -w
use strict;
CHOICE: print "
    This is Unit 6 - Quadrilaterals and Polygons.\n
    For the Final Exam, you will have to know the\n
    properties of all quadrilaterals and how to\n
    prove that a given shape is any quadrilateral.\n
    To access the Quadrilateral Information Database,\n
    type 'Quads.' To access the Casio-Maxim Quadrilateral\n
    Identification Algorithm, type 'crazy Maxim.'\n
    Type 'quit' to exit Unit 6.\n
    Type your choice.\n\n";
my $Choice = <STDIN>;
chomp $Choice;
if($Choice =~ /quit/i) {print "\nBye.\n\n"; exit;}
if($Choice =~ /quads/i) {require "Quadrilaterals.pl";}
if($Choice =~ /crazy maxim/i) {require "CMQIA.pl";}
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CMQIA.pl

 #!/usr/bin/perl -w
use strict;
ORIGINAL: print "
    Welcome to the Casio-Maxim Quadrilateral Identification\n
    Algorithm. In order to identify said quadrilateral,\n
    you must have the coordinates of all 4 vertices.\n";
PROMPT: print "
    When you are ready to input your coordines, type\n
    'ready.' Type anything else to exit the CMQIA.\n\n";
my $choice = <STDIN>;
if($choice =~ /ready/i) {goto MAXIM;}
if($choice !~ /ready/i) {require "Unit6.pl"; system("Unit6.pl"); requi
+re "Unit6.pl"; goto ORIGINAL;}
MAXIM: print "\nFor shape ABCD, in which point A has coordinates (X1, 
+Y1), B has coordinates\n\n(X2, Y2), C has coordinates (X3, Y3), and D
+ has coordinates (X4, Y4),\n\nX1 = ";
my $AX = <STDIN>;
chomp $AX;
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