use strict;
use warnings;

my %dict= ("\\begin\{enumerate\}" => "<ol>",
    "\\end\{enumerate\}" => "<\/ol>",
    "\\item\(.*\)" => "<li>\$1<\/li>");

 #my @array = ('\begin\{enumerate\}','\item(.*)','\end\{enumerate\}');

open(FILE, "latex.txt") or die $!;
open(OUT, "> out.txt") or die $!;
my $pattern;

while (my $line = <FILE>){
    foreach $pattern (keys %dict){
    $line =~ s/($pattern)/$dict{$1}/;
    }
    print $line;
    print OUT $line;
}