#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
void process_stack(int n) {
// Your logic here
int Stack[MAX] = { 0 };
char cmd[5] = { 0 };
int value = 0;
int top = -1;
for(int i =0; i < n; i++){
scanf("%s", cmd);
if(strcmp(cmd , "push") == 0) {
scanf("%d", &value);
(top == (MAX - 1)) ? printf("Stack Overflow\n") : Stack[++top] = value;
} else if (strcmp(cmd , "pop") == 0) {
(top < 0) ? printf("Stack Underflow\n") : printf("%d\n",Stack[top--]);
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}