def P(i, n, k,step = 0.2, Lambda = 0.01):
    other = F_
    if i > 0:
        return sum([
                P(i - 1, n, n - xk) * [1, 0.5][int(xk % n == 0)] * F_(k)*step
                for xk in range(n + 1)
                ])
    else:
        return 1-math.exp(-Lambda * k)