/**~*~*~*
CIS 22C
Project: Stack of strings (pop)

Written by: Iurii Tatishchev
IDE: CLion
*~*/
#include <iostream>
#include <string>

using namespace std;

class Stack_str {
private:
    // Structure for the stack nodes
    struct StackNode {
        string value;        // Value in the node
        StackNode *next;     // Pointer to next node
    };

    StackNode *top;          // Pointer to the stack top
    int length;

public:
    Stack_str(){ top = NULL; length = 0; }    //Constructor
    // ~Stack_str();                          // Destructor

    // Stack operations
    bool isEmpty() {
        return length == 0;
    }

    bool push(string);

    string pop();

    string peek() {
        return top->value;
    }

    int getLength() {
        return length;
    }
};

/**~*~*~*
  Member function push: pushes the argument onto the stack.
*~**/
bool Stack_str::push(string item) {
    StackNode *newNode; // Pointer to a new node

    // Allocate a new node and store num there.
    newNode = new StackNode;
    if (!newNode)
        return false;
    newNode->value = item;

    // Update links and counter
    newNode->next = top;
    top = newNode;
    length++;

    return true;
}

/**~*~*~*
  Member function pop pops the value at the top
  of the stack off, and returns it
  Assume stack is not empty
*~**/
string Stack_str::pop() {
    string val = this->top->value;

    StackNode* oldTop = this->top;
    this->top = this->top->next;
    this->length--;
    delete oldTop;

    return val;
}


int main() {

    Stack_str s;
    string item;

    getline(cin, item);
    while (item != "0") {
        s.push(item);
        cin.clear();
        getline(cin, item);
    }

    if (s.isEmpty()) cout << "Empty Stack!\n";

    while (!s.isEmpty()) {
        cout << s.pop() << "\n";
    }

    return 0;
}