my @substr_mat = ();
    my %map1       = ();
    my %map2       = ();

    foreach my $str (
        sort {
            ( $substrings{$b}[1] - $substrings{$b}[0] )
              <=> ( $substrings{$a}[1] - $substrings{$a}[0] )
              || $substrings{$a}[0] <=> $substrings{$b}[0]
        } keys %substrings
      )
    {
        my $substr_tmp1 = '';
        my $substr_tmp2 = '';

        foreach my $i ( $substrings{$str}[0] .. $substrings{$str}[1] ) {
            if ( !$map1{$i}++ ) {
                $substr_tmp1 .= "$s1[$i] ";
            }
        }
        next if !$substr_tmp1;

        foreach my $i ( $substrings{$str}[2] .. $substrings{$str}[3] ) {
            if ( !$map2{$i}++ ) {
                $substr_tmp2 .= "$s2[$i] ";
            }
        }
        next if !$substr_tmp2;

        push @substr_mat,
          ( length $substr_tmp1 <= length $substr_tmp2 )
          ? $substr_tmp1
          : $substr_tmp2;
    }