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