#!/usr/bin/perl
use strict;
use warnings;

my %institute_department_roll_name_mark_HoHoHoH = (
    CIA => {
        HUMINT => {
            rollno1  => {
                Bob     =>  65,
                Adam    =>  87,
            },
            rollno2  => {
                Dennis  =>  37,
                Arthur  =>  41,
            },
        },
        SIGINT => {
            rollno1  => {
                Harry   =>  87,
                Albus   => 100,
            },
            rollno2  => {
                M       =>  70,
                Q       =>  98,
                James   =>  75,
            },
        },
    },
    NSA => {
        Encryption => {
            rollno1  => {
                Abel    =>  13,
                Baker   =>  28,
                Charlie =>  57,
            },
            rollno2  => {
                Roger   =>   2,
                Fox     =>   3,
                Dog     =>   2,
            },
        },
        Decryption => {
            rollno1  => {
                Marin   =>  62,
                Chong   =>  66,
            },
            rollno2  => {
                Dave    =>   0,
            },
        },
    },
);

# Create a flattened data structure.
my $h1 = \%institute_department_roll_name_mark_HoHoHoH;
my @institute_department_roll_name_mark_AoH;
while             ( my ( $institute,  $h2   ) = each %{$h1} ) {
    while         ( my ( $department, $h3   ) = each %{$h2} ) {
        while     ( my ( $roll,       $h4   ) = each %{$h3} ) {
            while ( my ( $name,       $mark ) = each %{$h4} ) {
                push @institute_department_roll_name_mark_AoH, {
                    INST => $institute,
                    DEPT => $department,
                    ROLL => $roll,
                    NAME => $name,
                    MARK => $mark,
                };
            }
        }
    }
}

@institute_department_roll_name_mark_AoH = sort {
    $b->{MARK} <=> $a->{MARK}
 or $a->{INST} cmp $b->{INST}
 or $a->{DEPT} cmp $b->{DEPT}
 or $a->{ROLL} cmp $b->{ROLL}
 or $a->{NAME} cmp $b->{NAME}
} @institute_department_roll_name_mark_AoH;

for my $href (@institute_department_roll_name_mark_AoH) {
    printf  "%7d\t%-7s\t%-15s\t%-7s\t%s\n",
            @{$href}{qw( MARK INST DEPT ROLL NAME )};
}