#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
void process_stack(int n) {
// Your logic here
int stack[MAX];
int top = -1;
char op[10];
int value;
for (int i = 0; i < n; i++) {
scanf("%s", op);
if (strcmp(op, "push") == 0) {
scanf("%d", &value);
if (top == MAX - 1)
printf("Stack Overflow\n");
else
stack[++top] = value;
} else if (strcmp(op, "pop") == 0) {
if (top == -1)
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;
}