#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
void process_stack(int n) {
int stack[MAX];
int top = -1;
char cmd[20];
for(int i = 0 ;i < n; i++){
fgets(cmd, sizeof(cmd), stdin);
if(strncmp(cmd, "push", 4) == 0){
int val = atoi(cmd+5);
if(top >= MAX -1){
printf("Stack Overflow\n");
}else{
stack[++top] = val;
}
}
else if(strncmp(cmd, "pop", 3) == 0){
if(top < 0){
printf("Stack Underflow\n");
}else{
printf("%d\n", stack[top--]);
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}