#include<stdio.h>
void main(void)
{ 
	double x,y,result;
	char op;
	int flag;
	printf("input x,y,op:\n");
	scanf("%lf%lf%c",&x,&y,&op);
	flag=1;
	switch(op)
	{ 
		case '+':
			result=x+y;
			break;
		case '-':
			result=x-y;
			break;
		case '*':
			result=x*y;
			break;
		case '/':
			if(y) 
				result=x+y;
			else 
				flag=0; 
			break;
		default:
			flag=0;
	}
	if(!flag)
		printf("error input data\n");
	else
		printf("result=%f\n",result);
}