int den,flag,i;
double eps,item ,pi;
scanf("%lf",&eps) ;
i = 1;
flag = 1;
den = 1;
item = 1.0;
pi = 0;//fabs,求浮点数的绝对值,和abs相对
while(fabs(item)>=eps){
pi = pi+item;
i++;
flag = -flag;//符号隔一个一变
den = den +2;//分母每个加2
item = flag * 1.0/den;//1.0
}
pi = pi+item;
pi = pi* 4;
printf("%.5lf",pi);
printf("%d",i);