Stack: Balanced Brackets

Stack: are the brackets balanced

Read one line of brackets (( ) [ ] { }) and use a stack to decide whether they are balanced. Print 1 if balanced, 0 otherwise. The empty string is balanced.

This is the classic stack use. Complete isBalanced:

• On an opening bracket ( [ { → push.
• On a closing bracket → check the top is the matching opener: if so pop, otherwise (or if the stack is empty) it is unbalanced.
• After processing everything, the stack must be empty to be balanced.

Pitfalls (straight from the bug lab): (1) on a closing bracket with an empty stack, it is immediately unbalanced (do not pop an empty stack). (2) Check the type matches (] needs [, not (). (3) Don't forget the final empty check — ((( never hits a mismatch but the stack isn't empty, so it's unbalanced.

Input

• One line: the bracket string (may be an empty line).

Output

• One line: 1 (balanced) or 0 (not).

Example: input ([]) -> 1; input ([)] -> 0.