#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
using namespace std;
struct node{
    int u,v,m,h;
}que[100005];
bool cmp(struct node t1,struct node t2){
     if(t1.m==t2.m)
        return t1.u<t2.u;
     else
        return t1.m<t2.m;
}
int main(){
    int n;
    while(scanf("%d",&n)!=EOF){
            if(n==0)
            break;
    for(int i=0;i<n;i++){
        scanf("%d%d",&que[i].u,&que[i].v);
        que[i].h=(que[i].v-que[i].u)/2+1;
        que[i].m=que[i].u+que[i].h;
    }
    sort(que,que+n,cmp);
    int flag=0;
    for(int i=0;i<n-1;i++){
            if(que[i].m>=que[i+1].m){
                flag=1;
                break;
            }
        if(que[i].m<que[i+1].u)
            continue;
        double temp=que[i].m-que[i+1].u;
        que[i+1].m=temp+que[i+1].h+que[i+1].u;
    }
    if(flag)
        printf("NO\n");
    else
        printf("YES\n");


    }
   return 0;
}