#!/usr/bin/perl

open(FIL,"prob8data.txt");
$line = join('',<FIL>);
close(FIL);

$line =~ s/(\n|\r)//g;

$maxprod = 0;
for ($i = 0; $i < (length($line) - 5); $i++) {
  $n1 = substr($line,$i,1);
  $n2 = substr($line,$i+1,1);
  $n3 = substr($line,$i+2,1);
  $n4 = substr($line,$i+3,1);
  $n5 = substr($line,$i+4,1);
  $prod = $n1 * $n2 * $n3 * $n4 * $n5;
  if ($prod > $maxprod) {
    $maxprod = $prod;
  }
}
print "$maxprod\n";