stack problem

#include <iostream>
#include <string>
#include <vector>
using namespace std;

int arra[12], cmd;
void push(int x) {
    cmd++;
    arra[cmd] = x;
}

int pop() {
    int x = arra[cmd];
    cmd--;
    return x;
}

bool isEmpty() {
    if (cmd == -1) {
        return true;
    }
    return false;
}

int top() {
    return arra[cmd];
}

int main() {
    int n = 10;
    char str[6] = { '(', '[', '{', ')', ']', '}' };
    const char* vars = "((([][]{}))]";
    int abstr[12];
    for (int i = 0; i < 12; i++) {
        abstr[i] = 0;
        for (int j = 0; j < 6; j++) {
            if (vars[i] == str[j]) {
                abstr[i] = j;
                break;
            }
        }
    }
    cmd = -1;
    for (int i = 0; i < 12; i++) {
        if (abstr[i] < 3) {
            push(abstr[i]);
        }
        else {
            if (abstr[i] == arra[cmd] + 3) {
                pop();
            }
            else {
                cout << "this is not correct";
                return 0;
            }
        }
    }
    if (isEmpty()) {
        cout << "this is correct";
    }
    else {
        cout << "this is not correct";
    }
    return 0;
}