#include <bits/stdc++.h>
#include <boost/preprocessor/cat.hpp>

#define MY_CAT(a, b) a##b
#define c1 BOOST_PP_CAT(a, b)
#define c2 MY_CAT(a, b)

int main() {
    int ab = 512, a1 = 1024;
#define b 1
    printf("%d\n", c1);
    printf("%d\n", c2);
    return 0;
}