link list stack

#include <iostream>
#include <stdio.h>
#include <string.h>

using namespace std;

struct Node{
    int val;
    Node *next;
};

class Stack{
    private:
        Node *head = NULL;
        int size = 0;
    public:
        Stack(){
            size = 0;
        }
        void push_back(int in){
            Node *t1, *t2;
            t1 = head;
            while(t1 -> next != NULL)
                t1 = t1 -> next;
            t2 = new Node;
            t2 -> val = in;
            t2->next = NULL;
            t1->next = t2;
            size++;
        }
        void push_front(int in){
            Node *t;
            t = new Node;
            t -> val = in;
            if(head == NULL){
                t -> next = NULL;
                head = t;
            }
            else{
                t -> next = head;
                head = t;
            }
            size++;
        }
        int pop_back(){
            int val;
            if(head == NULL){
                cout << "Stack is Empty\n";
                return -1;
            }
            else{

                Node *t1;
                t1 = head;
                if(head -> next == NULL){
                    val = head -> val;
                    delete head;
                    return val;
                }
                else{
                    Node *chk = t1 -> next;
                    while(chk -> next != NULL){
                        t1 = chk;
                        chk = chk -> next;
                    }
                    val = t1 -> val;
                    delete chk;
                    t1 -> next = NULL;
                }
            }
            return val;
        }
        int pop_front(){
            int val;
            if (head == NULL){
                cout << "Stack is Empty\n";
                return -1;
            }
            else{
                Node *t1;
                t1 = head;
                if (head->next == NULL){
                    val = head->val;
                    delete head;
                    return val;
                }
                else{
                    head = head -> next;
                    val = head -> val;
                    delete t1;
                }
            }
            return val;
        }
        int top(){
            if(head == NULL) return -1;
            return head -> val;
        }
        void show(){
            Node *t;
            t = head;
            while(t != NULL){
                cout << t -> val << ' ';
                t = t -> next;
            }
            cout << endl;
        }
        int find(int in){
            Node *t;
            t = head;
            int index = 0;
            if(head == NULL) return -1;
            else{
                while(t != NULL){
                    index++;
                    if(t -> val == in) return index;
                    t = t -> next;
                }
            }
            return -1;
        }
        void del(){
            Node *t;
            while(head -> next != NULL)
            {
                t = head;
                head = head -> next;
                delete t;
            }
        }
        int length(){
            return size;
        }
};


int main(){
    Stack s;
    cout << "1. Push Front.\n";
    cout << "2. Push Back.\n";
    cout << "3. Pop Front.\n";
    cout << "4. Pop Back.\n";
    cout << "5. Print.\n";
    cout << "6. Top.\n";
    cout << "7. Search.\n";
    cout << "8. Exit.\n";
    while(true){
        int input, iin, delv;
        cin >> input;
        if(input == 1){
            cin >> iin;
            s.push_front(iin);
        }
        else if (input == 2)
        {
            cin >> iin;
            s.push_back(iin);
        }
        else if (input == 3)
        {
            delv = s.pop_front();
        }
        else if (input == 4)
        {
            delv = s.pop_back();
        }
        else if (input == 5)
        {
            s.show();
        }
        else if (input == 6)
        {
            cout << s.top() << endl;
        }
        else if (input == 7)
        {
            cin >> iin;
            if(s.find(iin) != -1) cout << "Found at " << s.find(iin) << " position\n";
            else cout << "Not Found\n";
        }
        else if (input == 8)
        {
            break;
        }
    }
    return 0;
}