#include <stdio.h>

int f(int* a, int b);

int main() {

    int a = 2, b = 3;
    a = f(&b, a);
    printf("a = %d, b = %d\n", a, b);
    b = f(&a, b) + 15;
    printf("a = %d, b = %d\n", a, b);

    return 0;
}

int f(int* a, int b) {

    int c = 3*(*a) - b;
    b = (c - *a)%12;
    *a = *a + b + c;
    printf("a = %d, b = %d\n", *a, b);
    return c;
}