#include <iostream>

using namespace std;

void factorialRecursion (int n, int& value) {
    if (n != 1){
        value *= n;
        factorialRecursion(--n, value);
    }
}

int factorial (int n) {
    if (n <= 0)
        return 0;

    int value = 1;
    factorialRecursion(n, value);

    return value;
}

void powerRecursion (int number, int& n, int& value) {
    if (n != 1) {
        value *= number;
        powerRecursion(number, --n, value);
    }
}

int power (int number, int n) {
    if (n == 0)
        return 1;

    int value = number;

    powerRecursion(number, n, value);

    return value;
}

float series (float x, int n) {
    int value = 2;
    float sum = 1;

    while (value != 2 * n) {
        sum += power(x, value) / factorial(value);

        value += 2;
    }

    return sum;
}

int main () {
    cout << series(2, 8) << endl;

    return 0;
}