Problem:
Score : 500 points

Problem Statement

We have a sequence of N integers: A_1, A_2, \cdots, A_N.

You can perform the following operation between 0 and K times (inclusive):

Choose two integers i and j such that i \neq j, each between 1 and N (inclusive). Add 1 to A_i and -1 to A_j, possibly producing a negative element.

Compute the maximum possible positive integer that divides every element of A after the operations. Here a positive integer x divides an integer y if and only if there exists an integer z such that y = xz.

Constraints

2 \leq N \leq 500

1 \leq A_i \leq 10^6

0 \leq K \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K
A_1 A_2 \cdots A_{N-1} A_{N}

Output

Print the maximum possible positive integer that divides every element of A after the operations.

Sample Input 1

2 3
8 20

Sample Output 1

7

7 will divide every element of A if, for example, we perform the following operation:

Choose i = 2, j = 1. A becomes (7, 21).

We cannot reach the situation where 8 or greater integer divides every element of A.

Sample Input 2

2 10
3 5

Sample Output 2

8

Consider performing the following five operations:

Choose i = 2, j = 1. A becomes (2, 6).

Choose i = 2, j = 1. A becomes (1, 7).

Choose i = 2, j = 1. A becomes (0, 8).

Choose i = 2, j = 1. A becomes (-1, 9).

Choose i = 1, j = 2. A becomes (0, 8).

Then, 0 = 8 \times 0 and 8 = 8 \times 1, so 8 divides every element of A. We cannot reach the situation where 9 or greater integer divides every element of A.

Sample Input 3

4 5
10 1 2 22

Sample Output 3

7

Sample Input 4

8 7
1 7 5 6 8 2 6 5

Sample Output 4

5

Solution in Python (3.4.3) (judge verdict: Accepted)

N, K = map(int, input().split())
a_list = list(map(int, input().split()))

def divisors(num):
    """
    約数全列挙
    """
    divisors = []
    for i in range(1, int(num ** 0.5) + 1):
        if num % i == 0:
            divisors.append(i)
            if i != num // i:
                divisors.append(num // i)

    return divisors
sum_num = sum(a_list)
a_list.sort()
div = divisors(sum_num)
div.sort(reverse=True)
ans = 1
from itertools import accumulate
for d in div:
    mod = []
    if d == 1:
        break
    for a in a_list:
        mod.append(a % d)
    mod.sort()
    acc_m = list(accumulate(mod))
    modd = []
    for i in range(N):
        modd.append(d-mod[i])
    acc_p = list(accumulate(modd))
    flag = False
    for i in range(N-1):
        p_sum = acc_p[-1] - acc_p[i]
        n_sum = acc_m[i]
        if p_sum == n_sum and p_sum <= K:
            flag = True
    if flag:
        ans = d
        break

print(ans)