#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 cmd[16];
int val;
for(int i=0; i<n; i++)
{
scanf("%s", &cmd);
if(strcmp(cmd, "push") == 0)
{
scanf("%d", &val);
if(top >= MAX - 1)
{
printf("Stack Overflow\n");
}
else
{
top++;
stack[top] = val;
}
}
else if(strcmp(cmd, "pop") == 0)
{
if(top < 0)
{
printf("Stack Underflow\n");
}
else
{
printf("%d\n", stack[top]);
top--;
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}