Danh sách liên kết đơn với số nguyên bị lỗi has stopped working

mn giúp e bài này với. e chạy bài này nhưng khi nhập xong nó ra cửa sổ exe has stopped working.
Là vì sao ạ?

#include<iostream>
using namespace std;
struct node{
	int data;
	struct node *next;
};
typedef struct node Node;
Node *getnode(int x){
	Node *p=new Node;
	Node *head;
	if(head == NULL) return NULL;
	else {
		p->data=x;
		p->next=NULL;
		return p;
	} 
}
void init(Node *head){
	head=NULL;
}
void themdau(Node *p){
	Node * newnode;
	p=newnode;
	Node *head;
	if(head==NULL) head=newnode;
	else {
		p->next=head;
		head=p;
	}
}
void in(Node *p){
	Node *head=p;
	if(head== NULL) cout<<"
 danh sach rong";
	cout<<"
 danh sach lien ket: 	";
	while(head!=NULL) {
		cout<<head->data <<"  -> " ;
		head=head->next;
	}
	cout<<head->data;
}
void themcuoi(Node *p){
	Node *head;
	Node *newnode=p;
	int x;
	p=getnode(x);
	while(head->next!=NULL){
		head=head->next;
	} 
	newnode->next=NULL;
	head->next=newnode;
}
void nhap(Node *p,int n){
	int x;
	for(int i=1;i<=n;i++){
		cout<<"
 nhap phan tu thu "<<i<< " : ";
		cin>>x;
		p=getnode(x);
		themcuoi(p);
	}
}
void chen(Node *p,int vt1){
	int dem=0;
	int x;
	Node *head,*temp;
	cout<<"
 nhap vi tri can chen: "; 	cin>>vt1;
	cout<<"
 nhap gia tri: ";cin>>x;
	p=getnode(x);
	while(head->next!=NULL){
		dem++;
	}
	if(vt1==1) {
		if(head==NULL){
			head=p;
			head->next=NULL;
		}
		p=head;
		head->next=p;
	}
	else if(vt1>1 && vt1<=dem){
		for(int i=1;i<vt1;i++){
			p=head;
			head=head->next;
		}
		head->next=p;
		p->next=head;
	}
	else cout<<" ngoai vi tri chen.";
}
int main(){
	int n,vt1;
	Node *p;
	cout<<"
 nhap so node: "; cin>>n;
	nhap(p,n);
	cout<<"
 danh sach lien ket: ";
	in(p);
	chen(p,vt1);
	return 0;

}