#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
void process_stack(int n) {
int stack[MAX];
int top = -1;
char line[50];
for (int i = 0; i < n; i++) {
fgets(line, sizeof(line), stdin);
line[strcspn(line, "\n")] = '\0';
if (strncmp(line, "push", 4) == 0) {
int value;
sscanf(line, "push %d", &value);
if (top == MAX - 1) {
printf("Stack Overflow\n");
} else {
stack[++top] = value;
}
}
else if (strcmp(line, "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;
}