// editor1

#include<stdio.h>

int top=-1, size=100, stack[100];

int isEmpty(){
    return top==-1;
}

int isFull(){
    return top==size-1;
}

void push(int data){
    if(isFULL()){
        printf(("Stack is Full\n");
    }
    stack[++top]=data;
}

void pop(){
    if(isEmpty()){
        printf("Stack is Empty\n");
        return;
    }
    top--;
}

void peek(){
    if(isEmpty()){
        printf("Stack is Empty\n");
    }
    printf("%d ", stack[top]);
}

void display(){
    if(isEmpty()){
        printf("Stack is Empty\n");
    }
    for(int i=0;i<top;i++){
        printf("%d ", stack[i]);
    }
}

int main(){
    scanf("%d", &n);
    if(n<0){
        printf("Invalid input")
        return 0;
    }
    for(int i=0;i<n;i++){
        char input[10];
        int data;
        scnaf("%s", input);
        if(input=="PUSH"){
            scanf("%d", &data);
            push(data);
        }else if(input=="POP"){
            pop();
        }else if(input=="PEEK"){
            peek();
        }else if(input=="DISPLAY"){
            display();
        }else{
            printf("Invalid input");
        }
    }
    return 0;
}