use strict;
my $str = '1.This is example of regex and call the mobile 400-199-1234.This statement is valid.2.This is second example of regex.10.This is tenth statement';
my $regex = qr/\b(?<!-)\d+\./mp;
my $subst = '';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html