RT

#include<bits/stdc++.h>
#define ll long long
using namespace std;
string s;
stack<char>s1;
ll cnt;
int main()
{
    cin>>s;
    for(int i=0;i<s.length();i++)
    {
    	if(s[i]=='(')s1.push(s[i]);
    	if(s[i]==')')
    	{
    		if(s1.top()=='(')s1.pop();
    		else s1.push(s[i]);
		 } 
	}
	cout<<s1.size();
   return 0;
}

https://iai.sh.cn/problem/614