Score : $500$ points

Problem Statement

There is an integer sequence $A$ of length $N$.

Find the number of the pairs of integers $l$ and $r$ ($1 \leq l \leq r \leq N$) that satisfy the following condition:

• $A_l\ xor\ A_{l+1}\ xor\ ...\ xor\ A_r = A_l\ +\ A_{l+1}\ +\ ...\ +\ A_r$

Here, $xor$ denotes the bitwise exclusive OR.

Constraints

• $1 \leq N \leq 2 \times 10^5$
• $0 \leq A_i < 2^{20}$
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

$N$

$A_1$ $A_2$ $...$ $A_N$

Output

Print the number of the pairs of integers $l$ and $r$ ($1 \leq l \leq r \leq N$) that satisfy the condition.

4
2 5 4 6

5

$(l,r)=(1,1),(2,2),(3,3),(4,4)$ clearly satisfy the condition. $(l,r)=(1,2)$ also satisfies the condition, since $A_1\ xor\ A_2 = A_1\ +\ A_2 = 7$. There are no other pairs that satisfy the condition, so the answer is $5$.

9
0 0 0 0 0 0 0 0 0

45

19
885 8 1 128 83 32 256 206 639 16 4 128 689 32 8 64 885 969 1

37