use warnings;
use strict;
use Data::Dumper;
$Data::Dumper::Useqq=1;

my $filename = 'cr835.txt';
open my $fh, '<', $filename or die "$filename: $!";
my $number;
while (<$fh>) {
	if ( m{ INC\*XX\* .* (?<!\d) (\d+) ~ $ }x ) {
		die "number matched twice" if defined $number;
		$number = $1;
	}
}
die "no number found" unless defined $number;
close $fh;

print Dumper($number);