#include <progrock/cppx/macro/nargs.h>          // CPPX_NARGS, CPPX_CONCAT
#include <progrock/cppx/macro/invoke.h>         // CPPX_INVOKE

#include <iostream>
using namespace std;

#define NUMBER_( x ) x

#define NUMBER_1( a ) \
    NUMBER_( a )

#define NUMBER_2( a, b ) \
    CPPX_CONCAT( NUMBER_1( a ), NUMBER_( b ) )

#define NUMBER_3( a, b, c ) \
    CPPX_CONCAT( NUMBER_2( a, b ), NUMBER_( c ) )

#define NUMBER_4( a, b, c, d ) \
    CPPX_CONCAT( NUMBER_3( a, b, c ), NUMBER_( d ) )

#define NUMBER_5( a, b, c, d, e ) \
    CPPX_CONCAT( NUMBER_4( a, b, c, d ), NUMBER_( e ) )

#define NUMBER( ... )      \
    CPPX_INVOKE( CPPX_CONCAT( NUMBER_, CPPX_NARGS( __VA_ARGS__ ) ), ( __VA_ARGS__ ) )

int main()
{
    wcout << NUMBER( 123,456,789 ) << endl;
}