#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 cmd[10];
int val;
for (int i = 0; i < n; i++){
scanf("%s",cmd);
if (strcmp(cmd, "push") == 0) {
scanf ("%d", &val);
if (top >= MAX - 1){
printf ("Stack Overflow\n");
} else {
stack[++top] = val;
}
} else if (strcmp(cmd, "pop") == 0) {
if (top == -1) {
printf("Stack Underflow\n");
} else {
printf("%d\n",stack[top]);
top--;
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}