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