You are given two arrays A and B consisting of N integers each.

Index K is named fair if the four sums (A[0] + ... + A[K-1]), (A[K] + ... + A[N-1]), (B[0] + ... + B[K-1]) and (B[K] + ... + B[N-1]) are all equal. In other words, K is the index where the two arrays, A and B, can be split (into two non-empty arrays each) in such a way that the sums of the resulting arrays' elements are equal.

write a function:

int fairIndexes(vector<int> &A, vector<int> &B);

which, given two arrays of integers A and B, returns the number of fair indexes.

The fair indices are 2 and 3. In both cases, the sums of elements in the subarrays are equal to 3.

For index 2;

4 + (-1) = 3; 0 + 3 = 3;

-2 + 5 = 3; 0 + 3 = 3;

The only fair index is 2.