#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
int stack[MAX];
int top = -1;
void push(int x) {
if (top == MAX - 1) {
printf("Stack Overflow\n");
return;
}
stack[++top] = x;
}
void pop() {
if (top == -1) {
printf("Stack Underflow\n");
return;
}
printf("%d\n", stack[top--]);
}
void process_stack(int n) {
for (int i = 0; i < n; i++) {
char line[20];
fgets(line, sizeof(line), stdin);
if (strncmp(line, "push", 4) == 0) {
int x;
sscanf(line + 5, "%d", &x);
push(x);
} else if (strncmp(line, "pop", 3) == 0) {
pop();
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consomme le saut de ligne
process_stack(n);
return 0;
}