I copied your script into a new file and validated its syntax

perl -c z3.pl 
z3.pl syntax OK
[download]

But then, I added use strict; on line 3 and did the same procedure

perl -c z3.pl 
Global symbol "$i" requires explicit package name at z3.pl line 6.
Global symbol "$input" requires explicit package name at z3.pl line 11
+.
Global symbol "$input" requires explicit package name at z3.pl line 12
+.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 13.
Global symbol "$input" requires explicit package name at z3.pl line 13
+.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 14.
Global symbol "$input" requires explicit package name at z3.pl line 15
+.
Global symbol "$input" requires explicit package name at z3.pl line 16
+.
Global symbol "$input" requires explicit package name at z3.pl line 18
+.
Global symbol "$input" requires explicit package name at z3.pl line 19
+.
Global symbol "@in" requires explicit package name at z3.pl line 20.
Global symbol "$input" requires explicit package name at z3.pl line 20
+.
Global symbol "$i" requires explicit package name at z3.pl line 24.
Global symbol "$final" requires explicit package name at z3.pl line 25
+.
Global symbol "@in" requires explicit package name at z3.pl line 25.
Global symbol "@in" requires explicit package name at z3.pl line 28.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 28.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 28.
Global symbol "$i" requires explicit package name at z3.pl line 29.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 31.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 31.
Global symbol "$fundcode" requires explicit package name at z3.pl line
+ 32.
Global symbol "@in" requires explicit package name at z3.pl line 32.
Global symbol "@in" requires explicit package name at z3.pl line 32.
Global symbol "@in" requires explicit package name at z3.pl line 32.
Global symbol "$outfile" requires explicit package name at z3.pl line 
+44.
Global symbol "$outfile" requires explicit package name at z3.pl line 
+45.
Global symbol "$final" requires explicit package name at z3.pl line 46
+.
Global symbol "$file" requires explicit package name at z3.pl line 52.
Global symbol "$file" requires explicit package name at z3.pl line 54.
Global symbol "$file" requires explicit package name at z3.pl line 54.
z3.pl had compilation errors.
[download]

And that matches line numbers (and a few more) where you are getting those messages.

No matter how simple the script may be use strict is not to be avoided and can save you some headaches.