def findmax(a, b, e):
    temp = abs(d1f(a))
    while (a < b):
        temp2 = abs(d1f(a))
        if temp2 > temp:
            temp = temp2
        a = a + e * 2
    return temp


def iter(a, b, e):
    c = a
    c_old = c + 2*e
    max = findmax(a, b, e)
    k = 0
    while (abs(c_old - c) >= e) and (abs(f(c)) >= e):
        c_old = c
        c = c_old - f(c) / max
        k = k + 1
    return c