#include<stdio.h>
#include<string.h>
#define MAX 100
int top=-1;
int arr[MAX];

int isFull(){
    if(top==MAX-1)
        return 1;
    else
        return 0;
}

void push(int num){
    if(isFull())
        printf("full");
    else
        arr[++top]=num;
}

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

void pop(){
    if (isEmpty())
         printf("Stack Underflow");
    else
         top--;
}

int peek(){
    if(isEmpty())
       printf("Stack Underflow");
       return 1;
    else
       return arr[top];
}

void display(){
    int i;
    for(int i=0;i<=top;i++){
    printf("%d",arr[i]);
    }
    printf("\n");
}
int main(){
    int size,i,num;
    char choice[20];
    scanf("%d\n",&size);
    if(size<0){
        printf("Invalid input");
        return 0;
    }
    for(i=0;i<size;i++){
        scanf("%s",choice);
        if(strcmp(choice,"PUSH")==0){
            scanf("%d",&num);