my @a = (43,43,44);
my @b = (43,43);
## Required result
my @c = (44);

my @p = ( 1,1,1,1,1,2,2,2,3,3,4,5,6);
my @q = ( 1,2,3,4,5,6 );
## Required result
my @r = ( 1,1,1,1,2,2,3 );