#!/usr/bin/perl -w reg.pl
my ($p, @q, $matchchar, $nummatch, $rep, $count, $q, $out);
$p = 'Terrence and Phillip are sweet';
$count = 0;
$matchchar = "e";
$nummatch = 3;
$repchar = "1";

@q = split (/(.*?)/, $p);
for($i = 0; $i < $#q + 1; $i++) {
	$_ = $q[$i];
	$count += 1 if (/$matchchar/);
	if (/$matchchar/ && ($count > $nummatch)) {
		$q[$i] = $repchar;
	}
}

$out = join ("", @q[0 .. $#q]);
print "out === $out";