#!/usr/bin/perl --
use strict;
use warnings;
Main( @ARGV );
exit( 0 );
sub Main {
    for my $outer ( 1 .. 3 ) {
        printf qq[%5s %5s %5s %5s \n], qw' out inn flip $1 ';
        for my $inner (1..10){
            my $flip =   $inner =~ /2/ .. $inner =~ /(5)/ ;
            printf qq[%5s %5s %5s %5s \n], $outer, $inner, $flip, $1 ||'';
        }
        print "\n";
    }
}
        
__END__
  out   inn  flip    $1
    1     1
    1     2     1
    1     3     2
    1     4     3
    1     5   4E0     5
    1     6           5
    1     7           5
    1     8           5
    1     9           5
    1    10           5

  out   inn  flip    $1
    2     1
    2     2     1
    2     3     2
    2     4     3
    2     5   4E0     5
    2     6           5
    2     7           5
    2     8           5
    2     9           5
    2    10           5

  out   inn  flip    $1
    3     1
    3     2     1
    3     3     2
    3     4     3
    3     5   4E0     5
    3     6           5
    3     7           5
    3     8           5
    3     9           5
    3    10           5