$c1=$c2=$c3=111222333444555; $c1=~ s/^(-?\d+)(\d{3})(\d{3})/$1,$2,$3/; $c2=~ s/^(-?\d+)(\d{3})(\d{3})(\d{3})/$1,$2,$3,$4/; $c3=~ s/^(-?\d+)(\d{3})(\d{3})(\d{3})(\d{3})/$1,$2,$3,$4,$5/; print<