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