Given a binary string $S$ consisting of characters `0`, `1`, and `?`. In one operation, you can:
- Change the character `0` to `1`.
- Change the character `?` to `0` or `1`.
- Swap two characters.
Determine the minimum number of operations required to transform the string $S$ into a binary string $T$.
### Input
- The first line contains the string $S$.
- The second line contains the string $T$.
### Output
- Print an integer representing the minimum number of operations. It is guaranteed that the answer exists.
### Constraints
- $1 \le |S| \le 300$.
### Sample test
Input:
```
0?1?
1001
```
Output:
```
3
```
