def step(a, n):
    for i in range(n):
        a *= a
    return a
def fct(n):
    a = 1
    for i in range(1, n + 1):
        a *= i
    return a
eps = float(input('Точность: '))
x = float(input('Икс: '))
i, summ = 0, 0
crr = step((-1), i) * step(x, 2 * i + 1) / fct(2 * i + 1)
nxt = step((-1), i + 1) * step(x, 2 * i + 2) / fct(2 * i + 2)
while nxt - crr >= eps:
    summ += crr
    crr = step((-1), i + 1) * step(x, 2 * i + 2) / fct(2 * i + 2)
    nxt = step((-1), i + 2) * step(x, 2 * i + 3) / fct(2 * i + 3)
    i += 1
print(summ)