#include <stdio.h>
#include <windows.h>

typedef int (__stdcall * mycallback)(int);

int do_callback( mycallback cb, int v) {
    int r = cb(v);
    return r;
}

int CALLBACK callback( int a) {
    printf("callback got %d\n", a);
    return a*2;
}


int main(int argc, char* argv[]) {
    int r;
    r = do_callback(callback, 21);
    printf("main got %d\n", r);
    return 0;
}