# pseudocode!!

# analize first line
my $line = <$fh>;
chomp $line;
# compute last index of the future array (or future string? be aware of possible off one errors!!);
my last = length $line - 1;
# rewind the filehandle
seek $fh,0,0;

sub get_column{
  my $col = shift;
  my $line = shift;
  if($col==0){$line=~/^(.)/}
  elsif($col==$last){$line=~/(.)$/}
  else{ $line=~/.{$col-1}(.)/} # or $last - $col? 
  return $1;
} 
while (<$fh>){
   chomp;
   print get_column(3,$_)

}