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: Time Limit Exceeded)

# coding: utf-8
# Your code here!
def divisor_list(N): #素因数分解
    res = []
    i = 1
    while i*i < N:
        if N%i == 0:
            res.append(i)
            res.append(N//i)
        i += 1
    if i*i == N: res.append(i)
    return sorted(res)

import sys
sys.setrecursionlimit(10**6)
readline = sys.stdin.readline #文字列入力のときは注意

n,k = [int(i) for i in readline().split()]
a = [int(i) for i in readline().split()]


l = reversed(divisor_list(sum(a)))


def check(x):
    res = []
    for ai in a:
        c = ai%x
        d = ai%x-x
        if abs(c) > abs(d): res.append(d)
        else: res.append(c)
    res.sort(key = abs)
    
    d = sum(res)

    if d > 0:
        idx = -1
        while d != 0:
            if res[idx]>0:
                d -= x
                res[idx] -= x
                idx -= 1
    if d < 0:
        idx = -1
        while d != 0:
            if res[idx]<0:
                d += x
                res[idx] += x
                idx -= 1
                
    c = sum([x for x in res if x > 0])        

#    print(x,c,res)
    return (c <= k)



for x in l:
    if check(x):
        print(x)
        exit()