use strict;
use warnings;

my $header = <DATA>;
while (my $line = <DATA> )
{
	chomp $line;
	my @array = split /;/, $line, -1;
	my $row_id = shift @array; 
	my @sorted = sort {$b<=>$a} @array;
	my $max = shift @sorted;
	my @index = map {$_ + 1} grep { $array[$_] eq $max } 0..$#array;
	print "Max value in the row $row_id is $max ";
	print "in the column(s) ",  @index > 1 ? join ',', @index : @index, ".\n";
}

__DATA__
row_id;value1;value2;value3
id001;10;10;30
id002;30;20;50
id003;30;80;10
id004;30;90;90
id005;50;50;10