#!/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 )};
}

##</code><code>##

    100 CIA     SIGINT          rollno1 Albus
     98 CIA     SIGINT          rollno2 Q
     87 CIA     HUMINT          rollno1 Adam
     87 CIA     SIGINT          rollno1 Harry
     75 CIA     SIGINT          rollno2 James
     70 CIA     SIGINT          rollno2 M
     66 NSA     Decryption      rollno1 Chong
     65 CIA     HUMINT          rollno1 Bob
     62 NSA     Decryption      rollno1 Marin
     57 NSA     Encryption      rollno1 Charlie
     41 CIA     HUMINT          rollno2 Arthur
     37 CIA     HUMINT          rollno2 Dennis
     28 NSA     Encryption      rollno1 Baker
     13 NSA     Encryption      rollno1 Abel
      3 NSA     Encryption      rollno2 Fox
      2 NSA     Encryption      rollno2 Dog
      2 NSA     Encryption      rollno2 Roger
      0 NSA     Decryption      rollno2 Dave