The problem is asking for the minimum number of parentheses that need to be added to make a given sequence of parentheses valid. The sequence contains four types of characters: `(`, `)`, `[`, and `]`.
Definition of a valid parentheses sequence:
- An empty string is a valid parentheses sequence.
- If A is a valid parentheses sequence, then `(A)` and `[A]` are also valid parentheses sequences.
- If A and B are valid parentheses sequences, then AB is also a valid parentheses sequence.
### Input
- One line containing a string S.
### Output
- Print an integer representing the minimum number of parentheses to be added.
### Constraints
- $1 \le |S| \le 100$.
### Sample test
Input:
```
[])
```
Output:
```
1
```
