#!/usr/local/bin/perl -w
use strict;
my $s = "Terence and Philip are sweet\n";
my $c = 'e';
my $r = 1;
my $n = 3;

sub mine
{
 my ($str,$chr,$new,$nbr)=@_;
 my $reg="(.+?)$chr" x --$nbr;
 $_=$str;
 (/$reg/)&&($str=$&)&&($_=$')&&(s/$chr/$new/g);
 return $str.$_;
}
print mine($s,$c,$r,$n);