// editor1
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int push();
int pop();
int peek();
int display();

int top=-1,arr[101];
int size;


int main()
{

 scanf("%d",&size);
   //arr[size];
  char str[20];
  scanf("%s",str);
  if(strcmp(str,"PUSH")==0)
  {
      push();
  }
   if(strcmp(str,"DISPLAY")==0)
  {
      display();
  }
  if(strcmp(str,"POP")==0)
  {
      pop();
  }
  
  
  if(strcmp(str,"PEEK")==0)
  {
      peek();
  }
  
 
  


}

int push()
{ 
    int val;
    scanf("%d",&val);
   
    else{
        arr[++top]=val;
    }
    
}
int pop()
{
    if(top==-1){
        
        printf("Stack Underflow");
        return 0;
    }
    else{
        top--;
    }
}
int peek()
{  
   printf("%d",arr[top]);
}

int display()
{
    for(int i=0;i<size;i++)
    {
        printf("%d ",arr[i]);
    }
}