Buggy python submission (verdict: Runtime Error):
import numpy as np
n, x = map(int, input().split())
ans = 1
def make_divisors(n):
    divisors = []
    for i in range(1, int(n**0.5)+1):
        if n % i == 0:
            divisors.append(i)
            if i != n // i:
                divisors.append(n//i)
    divisors.sort()
    return divisors
def check(n, li):
    for i in li:
        if i != 0:
            if abs(i) % n != 0:
                return False
    return True
li = list(map(int, input().split()))
li.append(x)
li = list(set(li))
li.sort()
start_index = li.index(x)
li = np.array(li)
if start_index == len(li)-1:
    n = li[start_index] - li[start_index - 1]
    n_div = make_divisors(n)
    for i in n_div[[-1]]:
        if check(i, li-x) and i > ans:
            ans = i
            break
        
elif start_index == 0:
    n = li[start_index+1] - li[start_index]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
else:
    n = li[start_index] - li[start_index - 1]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
    n = li[start_index+1] - li[start_index]
    n_div = make_divisors(n)
    
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
        if ans > i:
            break

print(ans)


Fixed submission:
import numpy as np
n, x = map(int, input().split())
ans = 1
def make_divisors(n):
    divisors = []
    for i in range(1, int(n**0.5)+1):
        if n % i == 0:
            divisors.append(i)
            if i != n // i:
                divisors.append(n//i)
    divisors.sort()
    return divisors
def check(n, li):
    for i in li:
        if i != 0:
            if abs(i) % n != 0:
                return False
    return True
li = list(map(int, input().split()))
li.append(x)
li = list(set(li))
li.sort()
start_index = li.index(x)
li = np.array(li)
if start_index == len(li)-1:
    n = li[start_index] - li[start_index - 1]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
        
elif start_index == 0:
    n = li[start_index+1] - li[start_index]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
else:
    n = li[start_index] - li[start_index - 1]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
    n = li[start_index+1] - li[start_index]
    n_div = make_divisors(n)
    
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
        if ans > i:
            break

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np
n, x = map(int, input().split())
ans = 1
def check(n, li):
    for i in li:
        if i != 0:
            if abs(i) % n != 0:
                return False
    return True
li = list(map(int, input().split()))
li.append(x)
li = list(set(li))
li.sort()
start_index = li.index(x)
li = np.array(li)
if start_index == len(li)-1:
    n = li[start_index] - li[start_index - 1]
    for i in reversed(range(1, n+1)):
        if check(i, li-x) and i > ans:
            ans = i
            break
        
elif start_index == 0:
    n = li[start_index+1] - li[start_index]
    for i in reversed(range(1, n+1)):
        if check(i, li-x) and i > ans:
            ans = i
            break
else:
    n = li[start_index] - li[start_index - 1]
    for i in reversed(range(1, n+1)):
        if check(i, li-x) and i > ans:
            ans = i
            break
    n = li[start_index+1] - li[start_index]

    for i in reversed(range(1, n+1)):
        if check(i, li-x) and i > ans:
            ans = i
            break
        if ans > i:
            break

print(ans)


Fixed submission:
import numpy as np
n, x = map(int, input().split())
ans = 1
def make_divisors(n):
    divisors = []
    for i in range(1, int(n**0.5)+1):
        if n % i == 0:
            divisors.append(i)
            if i != n // i:
                divisors.append(n//i)
    divisors.sort()
    return divisors
def check(n, li):
    for i in li:
        if i != 0:
            if abs(i) % n != 0:
                return False
    return True
li = list(map(int, input().split()))
li.append(x)
li = list(set(li))
li.sort()
start_index = li.index(x)
li = np.array(li)
if start_index == len(li)-1:
    n = li[start_index] - li[start_index - 1]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
        
elif start_index == 0:
    n = li[start_index+1] - li[start_index]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
else:
    n = li[start_index] - li[start_index - 1]
    n_div = make_divisors(n)
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
            break
    n = li[start_index+1] - li[start_index]
    n_div = make_divisors(n)
    
    for i in n_div[::-1]:
        if check(i, li-x) and i > ans:
            ans = i
        if ans > i:
            break

print(ans)