Buggy python submission (verdict: Runtime Error):
#D
import numpy as np
import math
def power(x, y, mod):
    if y == 0:
        t = 1
    elif y == 1:
        t = x % mod
    elif y % 2 == 0:
        t = (power(x, int(y/2), mod) ** 2) % mod
    else:
        t = (x * (power(x, int(y/2), mod) ** 2)) % mod
    return t
    
    
def frac_mod(n, mod, f=1):
    for i in range(1, n + 1):
        f = (f * i) % mod
    return f

def ifrac_mod(n, mod, f_inv=1):
    for i in range(n, 1, -1):
        f_inv = (f_inv * power(i, mod-2, mod)) % mod
    return f_inv

def cmb_mod(n, r, mod):
    n_frac = frac_mod(n, mod)
    n_r_ifrac = ifrac_mod(n-r, mod)
    r_ifrac = ifrac_mod(r, mod)
    
    return int((n_frac * n_r_ifrac * r_ifrac) % mod)
mod = 10**9+7
x,y = map(int, input().split())
a = np.array([[1,2], [2,1]])
b = np.array([x,y])
res = np.linalg.solve(a,b)
is_ok = True
if not (res[0].is_integer() and res[1].is_integer()):
    is_ok = False
    ans = 0
x_res = int(res[0])
y_res = int(res[1])
if is_ok:
    ans = cmb_mod(x_res+y_res, x_res, mod)
print(ans)

Fixed submission:
## D
import numpy as np
import math

def cmb(n, k, mod):
    numerator = 1
    for i in range(k):
        numerator = (numerator * (n-i)) % mod
 
    denominator = 1
    for i in range(1, k+1):
        denominator = (denominator * i) % mod
 
    return (numerator * pow(denominator, mod-2, mod)) % mod
    
    return int((n_frac * n_r_ifrac * r_ifrac) % mod)

mod = 10**9+7
x,y = map(int, input().split()) 
is_ok = True
b = (2 * x - y) / 3
a = x - 2 * b
if not (a.is_integer() and b.is_integer()):
    ans = 0
    is_ok = False
    
a = int(a)
b = int(b)
if a < 0 or b < 0:
    ans = 0
    is_ok = False
if is_ok:    
    ans = cmb(a+b, a, mod)
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
#D
import numpy as np
import math
def power(x, y, mod):
    if y == 0:
        t = 1
    elif y == 1:
        t = x % mod
    elif y % 2 == 0:
        t = (power(x, int(y/2), mod) ** 2) % mod
    else:
        t = (x * (power(x, int(y/2), mod) ** 2)) % mod
    return t
    
    
def frac_mod(n, mod, f=1):
    for i in range(1, n + 1):
        f = (f * i) % mod
    return f

def ifrac_mod(n, mod, f_inv=1):
    for i in range(n, 1, -1):
        f_inv = (f_inv * power(i, mod-2, mod)) % mod
    return f_inv

def cmb_mod(n, r, mod):
    n_frac = frac_mod(n, mod)
    n_r_ifrac = ifrac_mod(n-r, mod)
    r_ifrac = ifrac_mod(r, mod)
    
    return int((n_frac * n_r_ifrac * r_ifrac) % mod)
mod = 10**9+7
x,y = map(int, input().split())
a = np.array([[1,2], [2,1]])
b = np.array([x,y])
res = np.linalg.solve(a,b)
is_ok = True
if not (res[0].is_integer() and res[1].is_integer()):
    is_ok = False
    ans = 0
x_res = int(res[0])
y_res = int(res[1])
if is_ok:
    ans = cmb_mod(x_res+y_res, x_res, mod)
print(ans)

Fixed submission:
## D
import numpy as np
import math

def cmb(n, k, mod):
    numerator = 1
    for i in range(k):
        numerator = (numerator * (n-i)) % mod
 
    denominator = 1
    for i in range(1, k+1):
        denominator = (denominator * i) % mod
 
    return (numerator * pow(denominator, mod-2, mod)) % mod
    
    return int((n_frac * n_r_ifrac * r_ifrac) % mod)

mod = 10**9+7
x,y = map(int, input().split()) 
is_ok = True
b = (2 * x - y) / 3
a = x - 2 * b
if not (a.is_integer() and b.is_integer()):
    ans = 0
    is_ok = False
    
a = int(a)
b = int(b)
if a < 0 or b < 0:
    ans = 0
    is_ok = False
if is_ok:    
    ans = cmb(a+b, a, mod)
print(ans)