#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
typedef struct {
int buffer[MAX];
int head;
int capacity;
} Stack;
void process_stack(int n) {
char cmd[20] = {0};
int data;
Stack stk = {0};
stk.capacity = n;
while (n--) {
scanf("%s %d\n", cmd, &data);
if (!strncmp(cmd, "push", 4)) {
if (stk.head > (MAX - 1)) {
printf("Stack Overflow\n");
} else {
stk.buffer[stk.head++] = data;
}
} else if (!strncmp(cmd, "pop", 3)) {
if ((stk.head - 1) < 0) {
printf("Stack Underflow\n");
} else {
printf("%d\n", stk.buffer[--stk.head]);
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}