12345,John Dow,           123456
54321,ANDREW MALL,        8888882
987865,BOGGS BUNNY,       2234566
88777,CLARK KENT R,         888666
112222,DAVOLIO DARK F,          3321777

##</code><code>##

if( ($columns[0]!~/^[[:digit:]]+$/) || ($columns[2]!~/^[[:digit:]]+$/) ) {
#stop the program here
}