#include <stdio.h>

void swap(int* num1, int* num2) {
    int z = *num1;
    *num1 = *num2;
    *num2 = z;
}

int main() {
    int x = 19, y = 31;
    
    swap(&x, &y);

    printf("x = %d\ny = %d\n", x, y);
    return 0;
}