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

int top=-1,size=5;
inr arr[25];

int isEmpty(){
    if(top ==size-1){
        return 1;
    }else{
        return 0;
    }
}


int isFull(){
    if(top ==size-1){
        return 1;
    }else{
        return 0;
    }
}
void push(int num){
    if(isFull()){
        printf("Stack is Full\n");
    }else{
        
    }
    
}
void pop(){
    if(isEmpty()){
        printf("Stack is Empty");
    }else{
        
    }
}
int peek(){
    if(isEmpty()){
        return -1;
    }else{
        return arr[top];
    }
}

void travesal(){
    
}

int main() {
    int choice,num;
    
    while(1){
       scanf("%d",&choice);
       switch(choice){
           case 1:
                scanf("%d",&num);
                push(num);
                break;
            case 2:
                pop();
                break;
            case 3:
            int a==peek();
                if(a == -1){
                    
                }
                break;
            case 4:
                travesal();
                break;
            default:
                printf("Invalid input");
       }
    }


return 0;
}