【练】不允许创建临时变量，交换两个数的内容（附加题）

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int x = 5;
	int y = 9;
	x = x + y;
	y = x - y;
	x = x - y;
	printf("交换后的值为：x=%d y=%d\n",x,y);
	system("pause");
	return 0;
}