#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
void process_stack(int n) {
// Your logic here
int stack[MAX];
int index=0;
int val=0;
char str[8];
for(int i=0; i<n; i++){
scanf("%s", str);
if(strcmp(str, "push") == 0){
scanf("%d", &val);
if(index >= MAX){
printf("Stack Overflow\n");
}
else{
stack[index] = val;
index += 1;
}
}
else if(strcmp(str, "pop") == 0){
if(index <= 0){
printf("Stack Underflow\n");
}
else{
index -= 1;
printf("%d\n", stack[index]);
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}