#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#define EPSILON 0.0001

double factorial(double x)
{
    if (x <= 1) {
        return 1;
    } else {
        return x*factorial(x-1);
    }
}

int main()
{
    int x;
    printf("Enter x: ");
    scanf("%i", &x);

    double answer = 0;
    int sign = 1;      // For alternating signs
    for (int n = 0 ;; n += 2) {
        double new_term = sign * (pow(x, n) / factorial(n));
        answer += new_term;
        sign *= -1;

        if (abs(new_term) < EPSILON)
            break;
    }
    printf("Answer: %f\n", answer);
}