#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
void process_stack(int n) {
// Your logic here
int stack[MAX];
char cmd[10];
int top = -1;
int val = 0;
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;
}
}
if(strcmp(cmd, "pop") == 0){
if(top < 0){
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;
}