def solve(*s):
    sp = []
    if len(s) == 0 or len(s) > 3:
        return 'None'
    if s[0] == 0 and s[1] == 0 and s[1] == 0:
        sp.append("all")
        return sp
    elif s[0] == 0 and s[1] == 0:
        return []
    elif s[2] == 0:
        sp.append(0)
        sp.append((-1 * s[1]) / s[0])
        return sp
    elif s[0] == 0:
        sp.append(-s[2] / s[1])
        return sp
    else:
        d = s[1] ** 2 - 4 * s[0] * s[2]
        if d > 0:
            sp.append((-s[1] + d ** 0.5) / (2 * s[0]))
            sp.append((-s[1] - d ** 0.5) / (2 * s[0]))
            return sp
        if d == 0:
            sp.append(-s[1] / (2 * s[0]))
            return sp
        if d < 0:
            return sp