#include <iostream>
using namespace std;

class Lock {
public:
    void push(int button); // Simulates a digit button push
    bool open(); // Simulates a push of the open button
private:
    int combination = 1729; // Predefined combination
    int input = 0; // Digits entered by the user
};

void Lock::push(int button) {
    input = input * 10 + button; // Update input by appending the new digit
}

bool Lock::open() {
    if (input == combination) { // Check if entered combination matches predefined combination
        input = 0; // Reset input
        return true; // Return true if lock opens
    } else {
        input = 0; // Reset input regardless of correctness
        return false; // Return false if lock doesn't open
    }
}

int main() {
    Lock my_lock;
    my_lock.push(1);
    my_lock.push(7);
    my_lock.push(3);
    my_lock.push(9);
    cout << boolalpha;
    cout << my_lock.open() << endl;
    cout << "Expected: false" << endl;
    my_lock.push(1);
    my_lock.push(7);
    my_lock.push(2);
    my_lock.push(9);
    cout << my_lock.open() << endl;
    cout << "Expected: true" << endl;
    my_lock.push(1);
    my_lock.push(7);
    my_lock.push(2);
    cout << my_lock.open() << endl;
    cout << "Expected: false" << endl;
    my_lock.push(9);
    cout << my_lock.open() << endl;
    cout << "Expected: false" << endl;
    my_lock.push(1);
    my_lock.push(7);
    my_lock.push(2);
    my_lock.push(9);
    cout << my_lock.open() << endl;
    cout << "Expected: true" << endl;
    return 0;
}