# Original solution
class Factorial():
    def __init__(self, mod=10**9 + 7):
        self.mod = mod
        self._factorial = [1]
        self._size = 1
        self._factorial_inv = [1]
        self._size_inv = 1

    def __call__(self, n):
        return self.fact(n)

    def fact(self, n):
        ''' n! % mod '''
        if n >= self.mod:
            return 0
        self._make(n)
        return self._factorial[n]

    def fact_inv(self, n):
        ''' n!^-1 % mod '''
        if n >= self.mod:
            raise ValueError('Modinv is not exist! arg={}'.format(n))
        self._make_inv(n)
        return self._factorial_inv[n]

    def comb(self, n, r):
        ''' nCr % mod '''
        if r > n:
            return 0
        t = self.fact_inv(n-r)*self.fact_inv(r) % self.mod
        return self(n)*t % self.mod

    def comb_with_repetition(self, n, r):
        ''' nHr % mod '''
        t = self.fact_inv(n-1)*self.fact_inv(r) % self.mod
        return self(n+r-1)*t % self.mod

    def perm(self, n, r):
        ''' nPr % mod '''
        if r > n:
            return 0
        return self(n)*self.fact_inv(n-r) % self.mod

    @staticmethod
    def xgcd(a, b):
        '''
        Return (gcd(a, b), x, y) such that a*x + b*y = gcd(a, b)
        '''
        x0, x1, y0, y1 = 0, 1, 1, 0
        while a != 0:
            (q, a), b = divmod(b, a), a
            y0, y1 = y1, y0 - q * y1
            x0, x1 = x1, x0 - q * x1
        return b, x0, y0

    def modinv(self, n):
        g, x, _ = self.xgcd(n, self.mod)
        if g != 1:
            raise ValueError('Modinv is not exist! arg={}'.format(n))
        return x % self.mod

    def _make(self, n):
        if n >= self.mod:
            n = self.mod
        if self._size < n+1:
            for i in range(self._size, n+1):
                self._factorial.append(self._factorial[i-1]*i % self.mod)
            self._size = n+1

    def _make_inv(self, n):
        if n >= self.mod:
            n = self.mod
        self._make(n)
        if self._size_inv < n+1:
            for i in range(self._size_inv, n+1):
                self._factorial_inv.append(self.modinv(self._factorial[i]))
            self._size_inv = n+1

x, y = sorted(map(int, input().split()))
comb = Factorial().comb
q, r = divmod(x+y, 3)
if r != 0:
    print((0))
else:
    print((comb(q, y-q)))


# Optimized solution
MOD = 10**9 + 7
def xgcd(a, b):
    x0, y0, x1, y1 = 1, 0, 0, 1
    while b != 0:
        q, a, b = a // b, b, a % b
        x0, x1 = x1, x0 - q * x1
        y0, y1 = y1, y0 - q * y1
    return a, x0, y0

def modinv(a, mod):
    g, x, y = xgcd(a, mod)
    assert g == 1, 'modular inverse does not exist'
    return x % mod

factorials = [1]
def factorial(n, mod):
    # n! % mod
    assert n >= 0, 'Argument Error! n is "0 <= n".'
    if len(factorials) < n+1:
        for i in range(len(factorials), n+1):
            factorials.append(factorials[-1]*i % mod)
    return factorials[n]

def comb(n, r, mod):
    # nCr % mod
    assert n >= 0, 'Argument Error! n is "0 <= n".'
    assert n >= r >= 0, 'Argument Error! r is "0 <= r <= n".'
    
    return perm(n, r, mod) * modinv(factorial(r, mod), mod) % mod

def perm(n, r, mod):
    # nPr % mod
    assert n >= 0, 'Argument Error! n is "0 <= n".'
    assert n >= r >= 0, 'Argument Error! r is "0 <= r <= n".'
    return factorial(n, mod) * modinv(factorial(n-r, mod), mod) % mod

x, y = sorted(map(int, input().split()))
MOD = 10 ** 9 + 7
q, r = divmod(x+y, 3)
 
if r != 0:
    print((0))
else:
    try:
        print((comb(q, y - q, MOD)))
    except AssertionError:
        print((0))