You are given a binary string $S$. Count the number of non-empty substrings where the number of $0$ is equal to the number of $1$.
A substring is a consecutive sequence of characters within a string. For example, given the string `marisa`, `ris` is a substring, but `rsa` is not.
### Input
- The first line contains string $S$.
### Output
- Print 1 integers, the number of sastified substrings.
### Constraints
- $1 \le |S| \le 10^5$.
### Example
Input:
```
10010
```
Output:
```
4
```
