use strict;
use warnings;

my @aoa;
while (<DATA>) {
    chomp;
    push @aoa,[split '',$_];
    
}

foreach my $col(0..$#{$aoa[0]}){
  print "Column $col: ",
        (join ' ',map { $aoa[$_][$col] } 0..$#aoa),
        "\n";

}

__DATA__
ACATCACCTC
ACATCACCTC
ACATCACCTC
ACATCACCTC

# out 

Column 0: A A A A
Column 1: C C C C
Column 2: A A A A
Column 3: T T T T
Column 4: C C C C
Column 5: A A A A
Column 6: C C C C
Column 7: C C C C
Column 8: T T T T
Column 9: C C C C