#include<stdio.h>
#include<stdlib.h>

    int num,top=-1,size=5;
    int arr[25];
    scanf("%d",&num);
    
    int isFull(){
        if(top == size-1){
        return 1;
       }
       else{
           return 0;
       }
    }
    void push(int num){
        if(isFull()){
        printf("stack is full\n");
    }
    else{
        arr[++top];
    }
    
  }
  int isEmpty(){
        if(top == -1){
            return 1;
            }
        else{
            return 0;
        }
    }
    void pop(){
        if(isEmpty()){
             printf("stack is empty\n");
             
        }
        else{
            top--;
        }
}
void traverse(){
    for(int i=0;i<top;i++){
        if(num<0){
        printf("Invalid input");
        
    }
        scanf("%d",&size);
        push(num);
    }
  
}
int main{

    pop();
    traverse();
    return 0;
}