#!/usr/bin/perl

$hash{ substr $_, 0, 4  } .= $/ . substr($_, 4) for 1 .. 1000000;
$hash{$_} .= $/ foreach keys %hash;

$n=0;
print time, $/;
for (1 .. 1000000) {
  next unless exists $hash{ substr $_, 0, 4 }
  and 1+index( $hash{ substr $_, 0, 4 }, $/.substr($_, 4).$/ );
  $n++;
}
print time, $/, $n;