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

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

sub power2 {
    my( $n )= @_;
    return   if  ! $n;
    return(  ( $mask & pack "d", $n ) !~ /[^\0]/  );
}

for(  split " ", do { local($/); <DATA> }  ) {
    print "$_: ", power2($_)?1:0, "\n";
}
__END__
0 1 2 3 4 5 6 7 8 9 0.5 0.2 0.25 0.125 -1 -2 -3 -.25