#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define MAX 10
typedef struct{
int buffer[MAX]={0};
int head;
}stack;
void process_stack(int n) {
// Your logic here
stack buf;
char command[5];
buf.head=0;
for(int i=0;i<n;i++){
scanf("%s",command);
if(strncmp(command,"push",4)==0){
int num;
scanf("%d",&num);
if(buf.head<MAX)
buf.buffer[buf.head++]=num;
else
printf("Stack Overflow\n");
}else if(strncmp(command,"pop",3)==0){
int val;
if(buf.head>0){
val=buf.buffer[--(buf.head)];
printf("%d\n",val);
}else
printf("Stack Underflow\n");
}
}
}
int main() {
int n;
scanf("%d", &n);
getchar(); // Consume newline after number
process_stack(n);
return 0;
}