#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,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);
        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 || arriavl<0){
            printf("Invalid input");
            return 0;
        }
        enqueue(id,arrival);
    }
    dequeueALL();
    return 0;
}