You are given a bit string that consists of $n$ bits. Your task is to calculate the number of contiguous substrings that have an even number of ones.

Input

The only input line has a bit string which consists of $n$ bits.

Output

Print one integer: the number of substring with an even number of ones.

Example

Input:

01011

Output:

6

Subtask 1 (21 points)

• $1 \le n \le 100$

Subtask 2 (27 points)

• $1 \le n \le 5000$

Subtask 3 (52 points)

• $1 \le n \le 5 \cdot 10^5$