#include <stdio.h>
#include <math.h>
#define PI 3.1415927


long int factorial(int n)
{
	if (n<=1)
	return(1);
  else
	n=n*factorial(n-1);
	return(n);
 }
  	
int main (void)
{
	int answer, x, expon;
	float sums, first_term, error, next_term;
	double  y = 2/(sqrt(PI));
	long int factorial(int n);


	printf("Enter a number :");
	scanf("%i",&answer);
		if( answer == 0) {	//if answer is 0 the error is 0
			printf("The error is : 0 \n \n");
		}	//if block ends
	else {
		for (x = 1; x <= 5; ++x){
			if(x % 2 != 0){
				answer = answer *-1;
			}
			else{
				answer = answer * 1;
			}
			expon = 2 * x + 1; 
			first_term =  -1*( pow(answer,1) )/( 1 * factorial(0) );
			sums = first_term;
			next_term = (pow(answer,expon) )/ (expon * factorial(x) );
			sums = sums + next_term;
			error = y * sums;

		}	// for block ends for factorial
	
	printf("Error = %f \n", error);
	}
	
	return 0;
}