#!/usr/bin/perl --
use strict;
use warnings;
use CGI ();
use CGI::Carp qw(fatalsToBrowser);
use JSON ();

Main( @ARGV );
exit( 0 );
sub Main {
    binmode STDOUT;
    my $q  = CGI->new;
    my $cb = AddJsonGetBytes( $q );
    print $q->header("application/json"), $cb;
    return;
}
sub AddJsonGetBytes {
    my( $q ) = @_;
    my $data = $q->param('POSTDATA') ;
    my $json  = JSON->new->utf8;
    my $input = $json->decode( $data );
    my $a = $input->{a};
    my $b = $input->{b};
    my $c = $a + $b;
    return $json->encode({ c => $c });
}