hashtable simple

#include <iostream>
#include <string>
#define SIZE 20
using namespace std;

struct HashItems {
    int key;
    int value;
    HashItems *next;
    HashItems(int k, int val): key(k), value(val), next(NULL) {};
};

struct HashTable {
    HashItems *item;
};

HashTable htable[SIZE];

int get_simple_hash(int key) {
    return key % SIZE;
}

void insert(int value) {
    int hashkey = get_simple_hash(value);
    HashTable ht = htable[hashkey];
    HashItems *head = ht.item;
    if(head == NULL) {
        cout<<"No item at this key"<<endl;
        HashItems *firstItem;
        firstItem = new HashItems(hashkey, value);
        head = firstItem;
        ht.item = head;
        htable[hashkey] = ht;
    }
    else {
        cout<< "key already exists: avoid collision"<<endl;
        HashItems *node = head;
        while(node->next != NULL) {
            node = node->next;
        }
        HashItems *nthitem;
        nthitem = new HashItems(hashkey, value);
        node->next = nthitem;
        ht.item = head;
        htable[hashkey] = ht;
    }
}

void find(int value) {
    int hashkey = get_simple_hash(value);
    HashTable ht = htable[hashkey];
    HashItems *head = ht.item;

    if(head != NULL) {
        while(head!=NULL) {
            if(head->value == value) {
                cout<<"Found "<<value<<endl;
                return;
            }
            head = head->next;
        }
    }
    else {
        cout<<"not found" <<endl;
    }
}

int main() {
    insert(12);
    insert(90);
    insert(77);
    insert(32);

    find(90);
    find(32);
    find(44);
    return 0;
}