Given list of N integers and an integer K, find the number of ways to calculate the value of K  using those numbers with only addition and subtraction operations.

The first line contains 2 integers N and K
the next line contains N integers

one integer

In the example case: N = 4 K=2
we have: 
2
-1 -3 + 6 = 2
-1 + 3 = 2
1-2+3=2
1-2-3+6 = 2
There are 5 ways to get 2