import copy

class Polynom(object):

    def __init__(self, coefficients=[], degree=(-1)):
        self.coeff = copy.deepcopy(coefficients)
        l = len(self.coeff)
        if (degree >= l):
            self.coeff += [0 for i in range(degree + 1 - l)]

    def deg(self):
        return len(self.coeff) - 1

    def __getitem__(self, i):
        return self.coeff[i]

    def __setitem__(self, i, v):
        self.coeff[i] = v

    def trim(self):
        d = self.deg()
        i = d
        while i >= 0 and self[i] == 0:
            i -= 1
        if i < d:
            del self.coeff[i+1:]
        return self

    def __add__(self, p):
        d = max(self.deg(), p.deg())
        sum = Polynom(degree = d)
        for i in range(0, self.deg() + 1):
            sum[i] += self[i]
        for i in range(0, p.deg() + 1):
            sum[i] += p[i]
        return sum.trim()

    def __sub__(self, p):
        d = max(self.deg(), p.deg())
        sum = Polynom(degree = d)
        for i in range(0, self.deg() + 1):
            sum[i] -= self[i]
        for i in range(0, p.deg() + 1):
            sum[i] -= p[i]
        return sum.trim()

    def __mul__(self, p):
        if self.deg() < 0 or p.deg() < 0:
            return Polynom()
        d = self.deg() + p.deg()
        prod = Polynom(degree = d)
        for i in range(0, self.deg() + 1):
            for j in range(0, p.deg() + 1):
                prod[i + j] += self[i]*p[j]
        return prod

    def __str__(self):
        if self.deg() < 0:
            return "0"
        d = self.deg()
        s = ""
        for i in range(d, -1, -1):
            if i < d:
                s += " + "
            s += str(self[i])
            if i > 0:
                s += "x"
            if i > 1:
                s += "^" + str(i)
        return s

    def __repr__(self):
        return str(self)