How many subsets have the sum of x?

Consider we have a set of n numbers, and we want to calculate the number of subsets in which the addition of all elements equal to x.

Input first line has n, x and the next line contains n numbers of our set. In the output we have to calculate the number of subsets that have total sum of elements equal to x.

INPUT
4 3
-1 2 4 2

OUTPUT
2

constraints.??

refer to it

array = [1] + [0] * (sum)
pleas explain above?

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