#include <stdio.h>
#include <stdlib.h>
int stack[10000]={},top=0;
int i,j,n,x,n,p;
void push(int data)
{
stack[top++]=data;
}
void top1()
{
if(stack[top-1]==0)
{
printf("empty\n");
}
else
{
printf("%d\n",stack[top-1]);
}
}
char pop()
{
if(stack[top-1]<=0)
{
return stack[top];
}
else
{
return stack[--top];
}
}
void size()
{
printf("%d\n",top);
}
int main()
{
scanf("%d\n",&n);
for(j=0;j<n;j++)
{
scanf(" %c", &x);
if(x=='c')
{
size();
}
else if(x=='o')
{
top1();
pop();
}
else if(x=='i')
{
scanf("%d\n",&p);
push(p);
}
}
}