#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper qw/Dumper/;

my @array;
$array[0] = 'JHON 21 3999999 SCHOOL 1982-05-08';
$array[1] = 'JEFF 21 3999999 SCHOOL 1983-01-09';

my $current = undef;
my $prev = undef;
my %filtered = ();
foreach my $_array (@array){
    my @split = split(/\s/, $_array); 
 
    if (defined $filtered{$split[1]}{$split[4]}) 
    {
        substr($filtered{$split[1]}{$split[4]},0,1) = (++substr($filtered{$split[1]},0,1));
    }
    else {
        $filtered{$split[1]}{$split[4]} = "1\t$split[1]\t$split[2]";
    }
}
print Dumper( \%filtered );