$ perl -Mstrict -Mwarnings -E '
    my %x = ( a => { b => { d => 4, e => 5 }, c => 3 } );
    my $y = \%x;
    for (split /\// => $ARGV[0]) {
        last unless ref $y;
        $y = $y->{$_};
    }
    say $y if defined $y;
' a/c/e
3