[C++] Build ATM system

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

class my_Bank {

public:
    my_Bank () = default;
    my_Bank (string _PIN) : PIN(_PIN) {};
    my_Bank (const my_Bank& _my_Bank) : PIN(_my_Bank.PIN) {};
    my_Bank (const my_Bank&& _my_Bank) : PIN(std::move(_my_Bank.PIN)) {};
    ~my_Bank() = default;
    std::map <string, int>& operator[] (int idx){
        return Accounts[idx];
    }

    friend std::ostream& operator << (std::ostream& os, const my_Bank& _my_Bank);
    friend void pipeline (my_Bank& _my_Bank);
    friend void make_deposit(my_Bank& _my_Bank,int Acc_idx);
    friend void make_withdraw(my_Bank& _my_Bank,int Acc_idx);


private:
    string PIN;
    std::vector <std::map <string, int>> Accounts; // Account , Balance
    long long deposit = 0;
    bool withdraw = false;
};

std::ostream& operator << (std::ostream& os, const my_Bank& _my_Bank) {

    cout << "Good Bye !" << endl;
    cout << "Your PIN : " << _my_Bank.PIN << endl;
    cout << "There are " << _my_Bank.Accounts.size() << "Accounts " << endl;
    cout << endl;

    int idx = 1;

    for (auto it = _my_Bank.Accounts.begin(); it != _my_Bank.Accounts.end(); it++){
        cout << idx << ", " << it->begin()->first << ", balance : " << it->begin()->second << endl;
    }

    cout << "Thank you for visiting and have a nice day" << endl;

}


void make_deposit(my_Bank& _my_Bank,int Acc_idx) {

    bool process = true;

    while(process) {

        long long _deposit = 0;

        cout << "How much would you like to deposit ?" << endl;

        cin >> _deposit;

        _my_Bank.Accounts[Acc_idx].begin()->second += _deposit;

        cout << "Your have deposited : " << _deposit << "so, the balance will "
             << _my_Bank.Accounts[Acc_idx].begin()->second << endl;

        cout << "Is it correct ? [Y/N] " << endl;

        string YorN;

        cin >> YorN;

        if (YorN == "Y") {
            cout << "Deposit has complete, back to previous process" << endl;
            process = false;
            break;}
        else {
            cout << "Go back to deposit process, erase previous process" << endl;
            _my_Bank.Accounts[Acc_idx].begin()->second -= _deposit;
            _deposit = 0;
        }

    }

}

void make_withdraw(my_Bank& _my_Bank,int Acc_idx){

    bool process = true;

    while(process) {

        long long _withdraw = 0;

        cout << "How much would you like to deposit ?" << endl;

        cin >> _withdraw;

        _my_Bank.Accounts[Acc_idx].begin()->second -= _withdraw;

        cout << "Your have withdrawed : " << _withdraw << "so, the balance will "
             << _my_Bank.Accounts[Acc_idx].begin()->second << endl;

        cout << "Is it correct ? [Y/N] " << endl;

        string YorN;

        cin >> YorN;

        if (YorN == "Y") {
            cout << "Deposit has complete, back to previous process" << endl;
            process = false;
            break;}
        else {
            cout << "Go back to deposit process, erase previous process" << endl;
            _my_Bank.Accounts[Acc_idx].begin()->second += _withdraw;
            _withdraw = 0;
        }

    }
}

void pipeline(my_Bank& _my_Bank) {

    bool pipe_process = true;

    bool Acc_select = true;

    string Acc_idx;

    while (pipe_process) {

        while (Acc_select) {

            cout << "Please Select your Account" << endl;

            cout << "111-1111" << endl;
            cout << "222-2222" << endl;
            cout << "333-3333" << endl;

            cin >> Acc_idx;

            if (find(_my_Bank.Accounts.begin(), _my_Bank.Accounts.end(), Acc_idx) != _my_Bank.Accounts.end()) {

                cout << "Your Account is " << _my_Bank.Accounts[Acc_idx].begin()->first << endl;
                Acc_select = false;
                break;
            }
            else {
                cout << "Can't find valid Account, Please Enter Again" << endl;
                Acc_idx.clear();
            }
        }

        int choice;

        cout << "Next, Enter your Choice" << endl;
        cout << " 1 : Balance" << endl;
        cout << " 2 : Deposit" << endl;
        cout << " 3 : Withdraw" << endl;

        cin >> choice;

        cout << "Your choice is " << choice << endl;

        string YorN;

        switch (choice) {
            case 1: {
                cout << "Your Balance is "<<  _my_Bank.Accounts[Acc_idx]->second << endl;
                break;
            }

            case 2: {
                make_deposit(_my_Bank, Acc_idx);
                break;
            }

            case 3: {
                make_withdraw(_my_Bank, Acc_idx);
                break;
            }

            default: {
                cout << "Invalid Command, Please Enter Again" << endl;
                break;
            }
        }

        cout << "Do you need Another Service [Y/N]? " << endl;
        cin >> YorN;
        if (YorN == "Y") {
            cout << "Go back to previous process" << endl;
            pipe_process = true;
        }
        else {
            cout << "End of Process" << endl;
            pipe_process = false;
            break;
        }
    }
}

int main()
{
    cout << "Welcome, this it my bank" << std::endl;
    cout << "Please Enter your Card" << std::endl;

    string _PIN;

    std::cin >> _PIN;

    my_Bank my_bank(_PIN);

    pipeline(my_bank);

}