use strict ;
use warnings ;

open( my $fh, ">", "data1.txt" ) or die "Can't open > data1.txt: $!" ;
for my $i ( 1..1000 ) {
	print $fh "$i\n" ;
}
close $fh ;

open( $fh, ">", "data2.txt" ) or die "Can't open > data2.txt: $!" ;
for my $i ( 1001..2000 ) {
	print $fh "$i\n" ;
}
close $fh ;

open( $fh, ">", "data3.txt" ) or die "Can't open > data3.txt: $!" ;
for my $i ( 2001..3000 ) {
	print $fh "$i\n" ;
}
close $fh ;