Problem:
Score : 500 points

Problem Statement

Given are N integers A_1,\ldots,A_N.

We will choose exactly K of these elements. Find the maximum possible product of the chosen elements.

Then, print the maximum product modulo (10^9+7), using an integer between 0 and 10^9+6 (inclusive).

Constraints

1 \leq K \leq N \leq 2\times 10^5

|A_i| \leq 10^9

Input

Input is given from Standard Input in the following format:

N K
A_1 \ldots A_N

Output

Print the maximum product modulo (10^9+7), using an integer between 0 and 10^9+6 (inclusive).

Sample Input 1

4 2
1 2 -3 -4

Sample Output 1

12

The possible products of the two chosen elements are 2, -3, -4, -6, -8, and 12, so the maximum product is 12.

Sample Input 2

4 3
-1 -2 -3 -4

Sample Output 2

1000000001

The possible products of the three chosen elements are -24, -12, -8, and -6, so the maximum product is -6.

We print this value modulo (10^9+7), that is, 1000000001.

Sample Input 3

2 1
-1 1000000000

Sample Output 3

1000000000

The possible products of the one chosen element are -1 and 1000000000, so the maximum product is 1000000000.

Sample Input 4

10 10
1000000000 100000000 10000000 1000000 100000 10000 1000 100 10 1

Sample Output 4

999983200

Be sure to print the product modulo (10^9+7).

Solution in PyPy3 (7.3.0) (judge verdict: Wrong Answer)

n , k = map(int, input().split())
a = list(map(int, input().split()))
neg = []
pos = []
mod = 10**9+7
for i in range(n):
    if a[i] > 0:
        pos.append(a[i])
    else:
        neg.append(a[i])
neg.sort()
pos.sort(reverse = True)
min_num = -1
good_num = 0
if len(pos) == 0 or n == k:
    ans = 1
    a.sort(reverse = True)
    for i in range(k):
        ans *= a[i]
        ans %= mod
    print(ans % mod)
else:
    #最大化するとき
    from collections import deque
    ans = 1
    neg_new = []
    for i in range(0, len(neg)//2):
        neg_new.append(neg[2*i] * neg[2*i+1])
    neg_new = deque(sorted(neg_new, reverse = True))
    pos = deque(pos)
    if k % 2 == 1:
        k -= 1
        ans = pos.popleft()
    else:
        ans = 1
    while k > 0:
        if len(pos) >= 2 and len(neg_new) >= 1:
            if pos[0] * pos[1] > neg_new[0]:
                ans *= pos.popleft() * pos.popleft()
            else:
                ans *= neg_new.popleft()
        elif len(pos) >= 2:
            ans *= pos.popleft() * pos.popleft()
        else:
            ans *= neg_new.popleft()
        k -= 2
        ans %= mod
    print(ans % mod)