#!/usr/bin/env perl
use strict;
use warnings;
 
my $string  = ";the;fox;jumped;over;the;dog;the;duck;and;the;frog;";
my $pattern = qr{;the(?=;f)};
 
my $count;
 
$count++ while $string =~ m{
    (?&word){4}                         # Preceded by 4 words
    (?:
        (?= ( $pattern) ) (?&word)      # Match Pattern at 5th word
    |
        (?&word) (*SKIP)(*FAIL)         # Or consume 5th word and skip to next part of string.
    )
    (?(DEFINE)
        (?<word> ;[^;]*  ) 
    )
}xg;
 
print "Number of Matches = $count\n";
 

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