不允许创建临时变量，交换两个数的内容

#include<stdio.h>

void exchang(int *x,int *y)
{
*x = *x - *y;
*y = *x + *y;
*x = *y - *x;
printf("%d %d\n",*x,*y);
}
int main()
{
int a;
int b;
int *m=&a;
int *n=&b;
scanf("%d %d",&a,&b);
exchang( m,n);
return 0;
}