while True:
    t1 += deltat
    p0 = ((mu + lymbda * math.exp((-(lymbda + mu) * t1))) / (lymbda + mu))
    ans = abs(p0 - p0prev) / p0prev
    p0prev = p0
    print("t = {0} p0 = {1}  ans = {2}".format(round(t1,1), round(p0,5), ans))
    if (ans <= epsilon):
        break
print("Ответ:", round(t1,1))