// editor4
#include<stdio.h>
#include<stdlib.h>
struct node{
    int id;
    int arrival;
    struct node*next;
};
struct node* front=NULL;
struct node* rear=NULL;
void enqueue(int id,int arrival){
struct node*newnode=(struct node*)malloc(sizeof(struct node));
newnode->id=id;
newnode->arrival=arrival;
newnode->next=NULL;
if(rear==NULL){
    front=rear=newnode;
}
else{
    rear->next=newnode;
    rear=newnode;
}
}
void dequeueALL(){
    while(front!=NULL){
        printf("%d\n",front->id);
        struct node*temp=front;
        front=front->next;
        free(temp);
    }
}
int main(){
    int n;
    scanf("%d",&n);
    if(n<=0){
        printf("Invalid input");
        return 0;
    }
    for(int i=0;i<n;i++){
        int id,arrival;
        scanf("%d %d",&id,&arrival);
        if(id<=0||arrival<0){
            printf("Invalid input");
            return 0;
    }
    enqueue(id,arrival);
}
dequeueALL();
return 0
}