#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
void process_stack(int n) {
// Your logic here
int stack[MAX];
int top=-1;
char command[20];
int x;
for(int i=0;i<n;i++)
{
scanf("%s",command);
if(strcmp(command,"push")==0)
{
scanf("%d",&x);
if(top==MAX-1)
{
printf("Stack Overflow\n");
continue;
}
else
{
stack[++top]=x;
}
}
else if(strcmp(command,"pop")==0)
{
if(top==-1)
{
printf("Stack Underflow\n");
continue;
}
else
{
printf("%d\n",stack[top--]);
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}