简单计算法（我可没抄袭）

#include<iostream>
#include<string>
using namespace std;
int main()
{
    
    string a;
    int qianzhai = 0;
    getline(cin,a);
    for(int i=0;i > -1;i++)
    {
        if(a[i] == '(')
            qianzhai++;
        if(a[i] == ')')
        {
            if(qianzhai == 0)
            {
                cout << "NO";
                return 0;
            }
            else
                qianzhai--;
        }   
        if(a[i] == '@')
            break;
    }
    if(qianzhai == 0)
        cout << "YES";
    else
        cout << "NO";
    
    return 0;
}