C++ linked list user input out of bound validation causes pr

#include<iostream>
using namespace std;
int size;
struct node
{
	int orderId;
	string flavour;
	node *next;
};
class list
{
		private:
		node *head, *tail;
		public:
		list()
		{
			head=NULL;
			tail=NULL;
		}

		void display() //print out list
		{
			node *temp=new node;
			temp=head;

			if(head==NULL)
			{
				cout<<"You haven't ordered any cake(s)"<<endl;
			}

			while(temp!=NULL)
			{
				cout<<temp->orderId<<"\t"<<temp->flavour<<endl;
				temp=temp->next;
			}

		}

		void createnode(int orderId_value, string flavour_value) //create node at last position
		{
			node *temp=new node;
			temp->orderId=orderId_value;
			temp->flavour=flavour_value;
			temp->next=NULL;
			if(head==NULL)
			{
				head=temp;
				tail=temp;
				temp=NULL;
			}
			else
			{
				tail->next=temp;
				tail=temp;
			}
			size++;
		}

		bool update_data(int key) //update node data with given position
		{
		node *current=new node;
		current=head;
		string updated_flavour;

		if(head==NULL)
		{
			cout<<"No list"<<endl;
		}

		cout<<"Enter new flavour"<<endl;
		cin>>updated_flavour;

		for(int i=1;i<key;i++){
			current = current->next;
		}
			current->flavour=updated_flavour;

		}

		void delete_position(int pos) //delete node with given position
		{
			node *current=new node;
			node *previous=new node;
			current=head;

			if(head==NULL)
			{
				cout<<"You haven't ordered any cake(s)"<<endl;
			}

			for(int i=1;i<pos;i++)
			{
				previous=current;
				current=current->next;
			}
			previous->next=current->next;

			if(pos == 1){
				node *temp=new node;
			    temp=head;
			    head=head->next;
			    delete temp;
			}
			size--;
		}
};
int main()
{
	int orderId_input=0, destroy_input, position_input,checker;
	string flavour_input;

	list list; //created a list named list.
	list.display();

	cout<<"====Take 1===="<<endl;
	cout<<"Enter flavour for cake!"<<endl;
	cin>>flavour_input;

	orderId_input++;
	list.createnode(orderId_input,flavour_input);
	list.display();

	cout<<"====Take 2===="<<endl;
	cout<<"Enter flavour for cake!"<<endl;
	cin>>flavour_input;

	orderId_input++;
	list.createnode(orderId_input,flavour_input);
	list.display();

	cout<<"====Take 3===="<<endl;
	cout<<"Enter flavour for cake!"<<endl;

	cin>>flavour_input;

	orderId_input++;
	list.createnode(orderId_input,flavour_input);
	list.display();

	cout<<"====destroy node===="<<endl;
	cout<<"Which cake would you like to destroy?"<<endl;

	do{

	cin>>destroy_input;

	}while(destroy_input > size);

	list.delete_position(destroy_input);

	cout<<"====Result after destroy===="<<endl;
	list.display();
	cout<<"There are currently "<<size<<" cake(s)"<<endl;


	system("pause");

	return 0;
}