my %vals;
												
								 
while (<DATA>){
    chomp;
    my ($key, $val) = split;
    push @{$vals{$key}}, $val;
}

for my $key (sort {$a <=> $b} keys %vals) {
    my $max = max @{$vals{$key}};
    print "$key $max\n";
}			

I figured that , since my hint for a successful functioning of the code included parsing of excel using Spreadsheet::ParseExcel, I went ahead and added the code to the parsing one as such:
<code>
 #!/usr/bin/perl -w

    use strict;
	use warnings;
    use Spreadsheet::ParseExcel;
	use List::Util qw(max);
	

    my $parser   = Spreadsheet::ParseExcel->new();
    my $workbook = $parser->parse('4_19_10_Zrc01a-2.xls');

    if ( !defined $workbook ) {
        die $parser->error(), ".\n";
    }
   
    for my $worksheet ( $workbook->worksheets() ) {

        my ( $row_min, $row_max ) = $worksheet->row_range();
        my ( $col_min, $col_max ) = $worksheet->col_range();
        

        for my $row ( $row_min .. $row_max ) {
            for my $col ( $col_min .. $col_max ) {

     
		 my $cell = $worksheet->get_cell( $row, $col );
                next unless $cell;
		
						my %vals;
												
								 
while (<$col eq 5 and $col eq 8>){
    chomp;
    my ($key, $val) = split;
    push @{$vals{$key}}, $val;
}

for my $key (sort {$a <=> $b} keys %vals) {
    my $max = max @{$vals{$key}};
    print "$key $max\n";
}					  												 
																  }
												 
												  }
											  }