my $end = $#a1 < $#a2 ? $#a1 : $#a2; 
 my $result = 0; 
 for (my $l=0; $l<=$end; $l++) { 
  $result++ if $a1[$l] eq $a2[$l];  
 } 
 
 my $A = (2 * $result) / ($#a1 + $#a2 + 2); 
 my $B = $result / ($end+1); 
 print "Similar = $result, A = $A, B = $B\n"; 
} 
 
  
my $file = 'seqs.txt';  
open I, '<', $file 
or die "Can't open '$file' for reading: $!\n"; 
  
chop (%hash = map { split /\s*,\s*/,$_,2 } grep (!/^$/,<I>)); 
 
 
 
 print "$_$hash{$_}\n" for keys %hash; 
open  
open (IN, $ARGV[0]) || die "File not found $ARGV[0]: $!\n"; 
chomp(my @in = <IN>); 
 
 
map { 
  s/[^agtc]//ig; 
} @in; 
 
 
my $dna1 = read_file($ARGV[0]); 
my $dna2 = read_file($ARGV[1]); 
compare ($dna1, $dna2); 
 
compare($in[0], $in[1]); 
compare($in[1], $in[2]); 
compare($in[2], $in[3]); 
 
close (IN);