4. Matching Brackets

#include <iostream>
#include <string>
#include <stack>

using namespace std;

int main() {
    string expression;
    getline(cin, expression);

    stack<int> openBracketIndexes;

    for (size_t i = 0; i < expression.length(); i++) {
        if (expression[i] == '(') {
            openBracketIndexes.push(i);
        }
        else  if (expression[i] == ')') {
            cout << expression.substr(openBracketIndexes.top(), i - openBracketIndexes.top() + 1) << endl;
            openBracketIndexes.pop();
        }
    }

    return 0;
}