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