Stack Kartu

#include <iostream>
#include <string>
#define MAX 5

using namespace std;

struct Kartu {
    int angka;
    string jenis[MAX];
}K;

void entri(){
    K.angka = -1;
}

bool isEmpty() {
  return K.angka == -1;
}

bool isFull() {
    return K.angka == MAX-1;
}

void push() {
   if (isFull()) {
        cout<< "============================"<<endl;
        cout << "\nTumpukan penuh"<<endl;
        cout<< "============================"<<endl;
    }
    else {
    K.angka++;
    cout<< "==========================================="<<endl;
    cout << "\nMasukkan Angka Dan Jenis Kartu = "; cin.sync();getline(cin,K.jenis[K.angka]);
    cout << "Kartu " << K.jenis[K.angka] << " Masuk Ke Tumpukan Kartu"<<endl;
    cout<< "==========================================="<<endl;
    }
}

void pop() {
    if (isEmpty()) {
        cout<< "==========================================="<<endl;
        cout << "\nKartu Kosong\n"<<endl;
        cout<< "==========================================="<<endl;
    }
    else {
    cout<< "==========================================="<<endl;
    cout << "\nKartu "<<K.jenis[K.angka]<<endl;
    cout<< "==========================================="<<endl;
    K.angka--;
    }
}

void printKartu() {
    if (isEmpty()) {
        cout<< "==========================================="<<endl;
        cout << "Tumpukan Kartu Masih Kosong"<<endl;
        cout<< "==========================================="<<endl;
    }
    else {
    cout<< "==========================================="<<endl;
        for (int x = K.angka; x >= 0; x--)
            cout << "\nTumpukan Kartu ["<<x<<"]= "<< K.jenis[x] << ((x == 0) ? "" : " ");

    }
}

int main() {
    int pilihan, jenis;
    entri();
    cout<< "Nama Kelompok :  1. Feriyan Yusuf Arianto (06849)\n";
    cout<< "\t\t 2. Dion Rozin Kurnia Furqon (06859) \n"<<endl;
    do {
    printKartu();
    cout<<endl;
        cout << "\n1. Buka Kartu (Pop)\n";
        cout<<"2. Entri Kartu (push)\n";
        cout<<"3. Keluar\n";
        cout<<" Pilih Menu : ";
        cin >> pilihan;
        switch (pilihan)
        {
        case 1:
            pop();
            break;
        case 2:
            push();
            break;
        default:
      cout << "EXIT" << endl;
            break;
        }
    } while (pilihan!=3);
}