#include <iostream> //accept pin number and verify if correct

using namespace std;
int i,trans;
int pin[4];
int existingPin, trialPin, newPin;

void newPinz(){
	cout << "Please enter your new PIN: ";
					cin >> pin[0];
					existingPin=pin[0];

}

void changePin(){
		cout << "Please enter your existing PIN\n";
					for(i=0; i<4; i++){
					cin >> trialPin;
					if(trialPin == existingPin){
					cout << "Welcome " << existingPin <<"\n";
					cout << "Enter your new PIN ";
					cin >> newPin;
					existingPin = newPin;
					cout << "Your PIN has been changed \n";
					cout << endl;
					main();
					}
					else{
					cout <<"Error! Please enter PIN : ";}
				}
}

void existingPinz(){
		cout << "Please enter your existing PIN \n";
					for (i=1;i<4;i++){
					cin >> pin[i];
					if(existingPin == pin[i]){
					cout << "Validated, Welcome "<< existingPin <<endl;
					exit (0);
					}
					else{
					cout << "ERROR! PIN IS INCORRECT\n" << "Try again "<<"\n";
					main();
					}

				}
}

int main(){

	cout << "Welcome to BDO: Budie De Oro"<<endl;
	cout <<"<1>Enter New PIN" << endl << "<2>Change PIN" << endl<<"<3>Enter Existing PIN"<<endl;
		cin >> trans;
			switch(trans){
				case 1:
					newPinz();
					main();
				case 2:
					changePin();
					main();
				case 3:
				existingPinz();
}
}