#! perl -slw
use strict;
use List::Util qw[ max minstr maxstr ];
use Storable qw[ retrieve ];

my $h = retrieve '/path/to/yourfile';

for my $l1 ( keys %{ $h } ) {
    for my $l2 ( keys %{ $h->{ $l1 } } ) {
        printf "$l1->$l2: N: %d minL3: %s maxL3: %s minVal: %d\n",
            scalar( keys %{ $h->{ $l1 }{ $l2 } } ),
            minstr( keys %{ $h->{ $l1 }{ $l2 } } ),
            maxstr( keys %{ $h->{ $l1 }{ $l2 } } ),
            max(  values %{ $h->{ $l1 }{ $l2 } } );
    }
}