use strict and warnings, then clean up as many error and warning messages as you can.

With just warnings, I get:

Name "main::saw" used only once: possible typo at
Name "main::resultcode" used only once: possible typo at 
Unique result codes produced
Use of uninitialized value in concatenation (.) or string at 
Use of uninitialized value in concatenation (.) or string at 
Use of uninitialized value in concatenation (.) or string at 
Use of uninitialized value in concatenation (.) or string at 
Use of uninitialized value in concatenation (.) or string at 
Use of uninitialized value in concatenation (.) or string at 
2001 :  2007 :  5012 :  5011 :  5030 :  5033 :  Unique result codes pr
+oduced
[download]

With just strict, I get:

Global symbol "@saw" requires explicit package name at
Global symbol "$vtr" requires explicit package name at
Global symbol "$vtr" requires explicit package name at
Global symbol "%resultcode" requires explicit package name at 
Global symbol "$vtr" requires explicit package name at 
Execution ... aborted due to compilation errors.
[download]