#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
int stack[MAX];
int tail = 0;
void pop(void) {
if (tail == 0)
printf("Stack Underflow\n");
else
printf("%d\n", stack[tail-- - 1]);
}
void push(int val) {
if (tail == MAX)
printf("Stack Overflow\n");
else
stack[tail++] = val;
}
void process_stack(int n) {
for (int i = 0; i < n; i++) {
char cmd[32];
scanf("%s", &cmd[0]);
getchar();
//printf("cmd=%s\n", cmd);
if (strncmp(cmd, "pop", 3) == 0) {
pop();
} else {
int val;
scanf("%d", &val);
push(val);
getchar();
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}