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 Python (3.8.2) (judge verdict: Wrong Answer)

MOD = int(10e8)+7
def prod(arr):
    ans=1
    for i in arr:ans = (ans*i)%MOD
    return ans
n,k = map(int,input().split())
arr = list(map(int,input().split()))
arr.sort(key=abs,reverse = True)
def negs():
    return len([arr[i] for i in range(k) if arr[i]<0])%2==0
#print(arr)
candi = prod(arr[:k])
if negs() or k==n:
    print(candi%MOD)
else:
    nextPos = max(arr[k:])
    smallNeg = -1
    for i in range(k-1,-1,-1):
        if arr[i]<0:
            smallNeg = i
            break
    candi = 1
    for i in range(k):
        if i!=smallNeg:
            candi = (candi*arr[i])%MOD
    candi = (candi*nextPos)%MOD
    if nextPos<0:
        print(prod(arr[-k:])%MOD)
    else:
        print(candi%MOD)