@achievement = ('level A1', 'level A2', 'level A3', 'level A4', 
'level A5', 'level B1' , 'level B2', 'level B3', 'level B4', 
'level B5', 'level C1' , 'level C2', 'level C3', 'level C4', 'level C5', );

while (@achievement) {
     my $level = shift @achievement;
     push (@result, $level);
     print "Result: @result\n";
     }