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