giúp mik vs ạ c++ nha..............

#include <bits/stdc++.h>

using namespace std;

long long a, b, c = 1;
string n;

int main()
{
    //freopen("ngoac.inp", "r", stdin);
    //freopen("ngoac.out", "w", stdout);
    cin >> n;
    for(int i = 0; i < n.size(); i++){
        if(n[i] > 'A' && n[i] < 'Z'){
            c = -1;
            cout << "KHONG HOP LE";
            return 0;
        }
        else if(n[i] > 'a' && n[i] < 'z'){
            c = -1;
            cout << "KHONG HOP LE";
            return 0;

        }
        else if(n[i] == '(') a++;
        else if(n[i] == ')'){
            b++;
            if(a >= 1){
                a--;
                b--;
                c = 1;
            }
            else c = 0;
        }
    }
    if(a > 0 || b > 0) c = 0;
    if(c == 1) cout << "DUNG";
    else if(c == 0) cout << "KHONG DUNG";
    return 0;
}