/*sum of series of elements
1-x^2 / 2!+x^4 / 4!-x^6 / 6!+x^8 / 8!-x^10 /10!
*/

#include <stdio.h>
#include <math.h>
long facto(int);

void main()
{
    double x, sum = 1, flag = 0;
    long i;
    printf("Enter the value of x: ");
    scanf("%lf", &x);

    for (i = 2; i <= 10; i++)
    {
        if (flag == 0)
        {
            sum = sum - (pow(x, i) / facto(i));
            flag = 1;
        }
        else
        {
            sum = sum + (pow(x, i) / facto(i));
            flag = 0;
        }
    }

    printf("Sum of series of elements = %f\n", sum);
}

long facto(int n)
{
    long factorial;
    if (n == 1)
    {
        return 1;
    }
    else
    {
        factorial = n * facto(n - 1);
        return (factorial);
    }
}