#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int k;
    cout << "k="; cin >> k;
    float x;
    cout << "x="; cin >> x;
    float a = x;
    float s = a;
    cout << "a = " << a << endl;
    for (int i = 2; i <= k; i++) {
        a = (-1) * a * pow(x, 2) / ((2 * i - 1) * (2 * i - 2));
        s += a;
    }
    cout << "s = " << s << endl;
}