use strict;
use warnings;

use Test::More tests => 3;

my $in = 'Mary had a little lamb';

is (nwords ($in, 1), 'Mary');
is (nwords ($in, 2), 'Mary had');
is (nwords ($in, 3), 'Mary had a');

sub nwords {
    my ($src, $num) = @_;
    return join " ", (split (/ /, $src, $num + 1))[0 .. $num - 1];
}