#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--]);
}
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}