parentheis.cpp

#include <bits/stdc++.h>
#define _DEBUG
#define ll long long
#define pb push_back
#define REP(i, n) for (int i = 0; i < (int)n; i++)
#define REPI(i, a, b) for (int i = (a); (i <= (b)); ++i)
#define x first
#define y second
using namespace std;

///REF PII

typedef pair<int, int> pii;

const int INF = 2e9;
const ll INF64 = 1e18;
const int M = 2 * 1000 * 1000;
const int N = 300 * 1000 + 100;
const int MOD = 1e9 + 7;
const double EPS = 1e-9;
const double PI = 3.14159265359;

template <typename T>
T gcd(T x, T y)
{
	if (y == 0)
	{
		return x;
	}
	return gcd(y, x % y);
}

bool sortbysec(const pair<int, int> &a, const pair<int, int> &b)
{
	return (a.second < b.second);
}

void solve()
{
	string s;
	cin >> s;

	stack<char> stk;
	bool push = true;
	int count = 0;

	stk.push(s[0]);

	for (int i = 1; i < s.length(); i++)
	{
		push = true;

		if (s[i] == ')')
		{
			if (!stk.empty() && stk.top() == '(')
			{
				count++;
				stk.pop();
				push = false;
			}
		}
		if (push)
		{
			stk.push(s[i]);
		}
	}

	cout << count << endl;
}

int main()
{
#ifdef _DEBUG
	freopen("input.txt", "r", stdin);
	// freopen("output.txt", "w", stdout);
	int tt = clock();
#endif

	ios_base::sync_with_stdio(false);
	int no_of_test_cases;
	//cin >> no_of_test_cases;
	no_of_test_cases = 1;
	while (no_of_test_cases--)
	{
		solve();
	}

#ifdef _DEBUG
	cerr << "TIME = " << clock() - tt << endl;
	tt = clock();
#endif

	return 0;
}