#include <stdio.h>
#include <stdlib.h>
#define EPS 1e-5
int main(void)
{
	double x,a,n,s,r;
	printf("enter x\n");
	scanf("%lf",&x);
	s=0;
	a=-x*x;
	n=1;
	r=x;
	while(r>EPS || r<-EPS)
	{
		s+=r;
		n+=2;
		r*=(-1)*a/(n*(n+1));
	}
	printf("%lf",s);
	system("pause");
	return 0;
}