Hi, I made this modification:

#!/usr/local/bin/perl 
open my $FILE, '<', 'rapipago.txt' or die "Cannot open file1.txt: $!";
my $outfile = "rapipagomod.txt";
open my $out, '>', $outfile or die "can't open $outfile: $!\n";
use strict;
use warnings;
use feature 'say';
while (my $text = <$FILE>) {
    chomp $text;
    my @cums = (0);
    my @offs = ( 17, 6, 31, 3, 3 );
    my @cums = ( 0 );
    push @cums, $_ + $cums[ -1 ] for @offs;
    substr $text, $_, 0, q{-} for reverse @cums[ 1 .. $#cums ];
say $outfile $text;
}
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And I am receiving this error:
"Can't use string ("rapipagomod.txt")as a symbol ref while "strict refs" in use at C:\Users\ARIBIA~1\Desktop\Rapipago.pl line 15, <$FILE> line1."