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 PyPy3 (2.4.0) (judge verdict: Accepted)

import sys,math
printn = lambda x: sys.stdout.write(x)
inn = lambda : int(input())
inl   = lambda: list(map(int, input().split()))
inm   = lambda:      map(int, input().split())
DBG = True  and False

def ddprint(x):
  if DBG:
    print(x)

def prime_division(x):
    q = int(math.sqrt(x))
    a = []
    for i in range(2,q+1):
        ex = 0
        while x%i == 0:
            ex += 1
            x //= i
        if ex>0:
            a.append([i,ex])
    if x>q:
        a.append([x,1])
    return a

def divisorlist(z):
    if len(z)==1:
        return [z[0][0]**i for i in range(z[0][1]+1)]
    y = divisorlist(z[1:])
    s = []
    for i in range(z[0][1]+1):
        for j in y:
            s.append((z[0][0]**i)*j)
    return s

n,k = inm()
a = inl()
sm = sum(a)
zz = prime_division(sm)
z = divisorlist(zz)
z.sort(reverse=True)
ddprint(z)
for p in z:
    if p>sm+k:
        continue
    b = [ai%p for ai in a]
    b.sort()
    s = sum(b)
    m = s//p
    t = sum(b[:n-m])
    ddprint("p {} b {} s {} m {} t {}".format(p,b,s,m,t))
    if t<=k:
        print(p)
        exit()