#define Я_РУССКИЙ "Russian"
#include <fstream>
#include <iostream>
using namespace std;

void main() {
    setlocale(LC_ALL, Я_РУССКИЙ);

    int a = 1, n = 0, f = 0;
    long double b = 1, c = 1;
    double x, e, result = 0, prevResult = 0;
    cin >> x >> e;
    do {
        prevResult = result;
        cout << "n= " << n << "\t a = " << a << "\t b= " << b << "\t c= " << c << "\t [[a/b * c = " << (double) a / b * c << "]]" << endl;
        result += (double) a / b * c;

        n = n + 1; f += 2;
        a = a * -1;
        b = b * (f - 1) * f;
        c = c * x * x;
    } while (abs(result - prevResult) > e);

    cout << result << endl;
}