Consider the following C program snippet:

void swap(int x, int y);

int main() {

    int a = 10, b = 20;

    swap(a, b);

    printf("%d %d", a, b);

    return 0;

}

void swap(int x, int y) {

    x = x + y;

    y = x - y;

    x = x - y;

}

Which of the following is TRUE?