Where and how would I add code that allows the user to choose if they want to include nuts or citrus instead of automatically choosing?

//Snack.Java

public class Snack {

private String id;

private String size;

private double price;

public Snack(String id, String size) {

setId(id);

setSize(size);

this.size = size;

if(size.equals("S"))

setPrice(19.99);

else if(size.equals("M"))

setPrice(29.99);

else if(size.equals("L"))

setPrice(39.99);

}

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getSize() {

return size;

}

public void setSize(String size) {

this.size = size;

}

public double getPrice() {

return price;

}

public void setPrice(double price) {

this.price = price;

}

public String toString() {

return "ID: "+id+" Size: "+size+" Price: "+price;

}

}

//SaltySnack.java

public class SaltySnack extends Snack {

private boolean isNutSnack;

public SaltySnack(String id, String size,boolean isNutSnack) {

super(id, size);

setNutSnack(isNutSnack);

if(isNutSnack)

setPrice(getPrice()+4.50);

}

public boolean isNutSnack() {

return isNutSnack;

}

public void setNutSnack(boolean isNutSnack) {

this.isNutSnack = isNutSnack;

}

public String toString() {

return "Salty Snack "+super.toString()+" Is nut snack: "+isNutSnack;

}

}

//FruitSnack.java

public class FruitSnack extends Snack {

private boolean isCitrus;

public FruitSnack(String id, String size,boolean isCitrus) {

super(id, size);

setCitrus(isCitrus);

if(isCitrus)

setPrice(getPrice()+5.99);

}

public boolean isCitrus() {

return isCitrus;

}

public void setCitrus(boolean isCitrus) {

this.isCitrus = isCitrus;

}

public String toString() {

return "Fruit Snack "+super.toString()+" Is citrus fruit: "+isCitrus;

}

}

//Main.java

import java.util.Scanner;

public class OrderSystem {

public static Scanner sc=new Scanner(System.in);

public static void menu() {

System.out.println(" O-Order Snack.");

System.out.println("E-Exit.");

System.out.print("Enter choice(O,E): ");

}

public static void submenu() {

System.out.println(" F-Fruit Snack");

System.out.println("S-Salty Snack");

System.out.print("Enter choice(F,S): ");

}

public static void sizeMenu() {

System.out.println(" S-Small");

System.out.println("M-Medium");

System.out.println("L-Large");

System.out.print("Enter choice(S,L,M): ");

}

public static String input() {

String str=sc.nextLine();

return str;

}

public static void displayOrder(String type,String size) {

Snack snack;

if(type.equals("F")) {

snack=new FruitSnack("12FF",size,true);

System.out.println(snack);

}

else if(type.equals("S")) {

snack=new SaltySnack("11SS",size,false);

System.out.println(snack);

}

else

System.out.println(" Invlid input!");

}

public static void order() {

String type,size;

submenu();

type=input();

if(type.equals("F") || type.equals("S")) {

sizeMenu();

size=input();

if(size.equals("S") || size.equals("M") || size.equals("L"))

displayOrder(type,size);

else

System.out.println(" Invlid input!");

}

else

System.out.println(" Invlid input!");

}

public static void run() {

String ch="";

do {

menu();

ch=input();

if(ch.equals("O"))

order();

else if(ch.equals("E"))

break;

else

System.out.println(" Invlid input!");

}while(true);

}

public static void main(String[] args) {

run();

}

}