Problem:
Score : 300 points

Problem Statement

Tak has N cards. On the i-th (1 \leq i \leq N) card is written an integer x_i.
He is selecting one or more cards from these N cards, so that the average of the integers written on the selected cards is exactly A.
In how many ways can he make his selection?

Constraints

1 \leq N \leq 50

1 \leq A \leq 50

1 \leq x_i \leq 50

N,\,A,\,x_i are integers.

Partial Score

200 points will be awarded for passing the test set satisfying 1 \leq N \leq 16.

Input

The input is given from Standard Input in the following format:

N A
x_1 x_2 ... x_N

Output

Print the number of ways to select cards such that the average of the written integers is exactly A.

Sample Input 1

4 8
7 9 8 9

Sample Output 1

5

The following are the 5 ways to select cards such that the average is 8:

Select the 3-rd card.

Select the 1-st and 2-nd cards.

Select the 1-st and 4-th cards.

Select the 1-st, 2-nd and 3-rd cards.

Select the 1-st, 3-rd and 4-th cards.

Sample Input 2

3 8
6 6 9

Sample Output 2

0

Sample Input 3

8 5
3 6 2 8 7 6 5 9

Sample Output 3

19

Sample Input 4

33 3
3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

Sample Output 4

8589934591

The answer may not fit into a 32-bit integer.

Solution in Python (3.8.2) (judge verdict: Runtime Error)

from collections import deque

n,a=map(int,input().split())
cards=list(map(int,input().split()))


noz=[x-a for x in cards].count(0)
pl=[x-a for x in cards if x-a>0]
nl=[a-x for x in cards if x-a<0]
sl=[pl,nl][len(nl)<=len(pl)]
ll=[pl,nl][len(pl)<len(nl)]

sl.sort()
ll.sort()

nsl=len(sl)
nll=len(ll)

sumsl=[sum([sl[x]*((i>>x)&1) for x in range(nsl)]) for i in range(1,2**nsl)]
# print(sl,ll,sumsl)
count=0
for i in range(1,nll+1):
    if sumsl[-1]< sum([ll[x]*(((2**i)>>x)&1) for x in range(nll)]):
        continue

for j in range(1,2**i):
    s=sum([ll[x]*((j>>x)&1) for x in range(nll)])
    count+=(s in sumsl)

print((count+1)*(2**noz)-1)