#include <stdio.h>

void swap(int *a, int *b) {
    int tmp = *a;
    *a = *b;
    *b = tmp;
}

int main() {
    int x = 6;
    int y = 3;

    printf("%d %d\n", x, y);
    swap(&x, &y);
    printf("%d %d\n", x, y);


    return 0;
}