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