#include<stdio.h>
#include<ctype.h>
void main(void)
{ 
	int c,sign,result;
	printf("input a string [digits]:\n");
	for(c=getchar();isspace(c);c=getchar());
		sign=(c=='-')?-1:1;
	if(c=='+'||c=='-')
		c=getchar();
	for(result=0;isdigit(c);
	c=getchar())
	result=10*result+c-'0';
	result*=sign;
	printf("result=%d\n",result);
}