0 == 0 == 0
1 <= 1 <= 1
2 <= 2 <= 2
2 <= 3 <= 4
4 <= 4 <= 4
4 <= 5 <= 8
16384 <= 32000 <= 32768
8589934592 <= 10000000000 <= 17179869184
-2 >= -2 >= -2
-2 >= -3 >= -4
0.0625 <= .1 <= 0.125
0.0078125 <= .01 <= 0.015625
-0.0009765625 >= -.001 >= -0.001953125
5.61779104644474e+306 <= 1e307 <= 1.12355820928895e+307
8.98846567431158e+307 <= 1e308 <= 1.#INF
8.90029543402881e-308 <= 1e-307 <= 1.78005908680576e-307

##</code><code>##

#!/usr/bin/perl -w
use strict;

my $mant;
BEGIN {
    my $max= 2;
    $max *= 2   until  2*$max+1 == 2*$max;
    $mant= pack("d",$max) ^ pack("d",2*$max-1);
}

sub prevPower2 {
    my( $n )= @_;
    return  unpack "d", ~$mant & pack "d", $n;
}

sub nextPower2 {
    my( $n )= @_;
    my $p= prevPower2( $n );
    $p *= 2   if  $p != $n;
    return  $p;
}

while(  <>  ) {
    chomp;
    my $dir= (qw( < = > ))[ 1 + (0<=>$_) ];
    print prevPower2($_), " $dir= $_ $dir= ", nextPower2($_), $/;
}