use Data::Dumper;

my $n = 5;
my %hash;
@hash{ 0..100_000 } = 0..100_000;
print time, "\n";
my %temp;
@temp{(keys(%hash))[0..4]} = (values(%hash))[0..4];
%hash = %temp;
print time, "\n";
print Dumper(\%hash);