#include<iostream>

#include<string.h>

#include<math.h>

#include <stdio.h>

#include <algorithm>

using namespace std;

struct node

{

    int s,t;

    int m;

};

node a[];

int cmp(node a,node b)

{

    return a.m<b.m;

}

int main()

{

    int n;

    int i,j;

    int now;

    while(scanf("%d",&n)!=EOF)

    {

        if(n==)

            break;

        for(i=;i<n;i++)

        {

            scanf("%d%d",&a[i].s,&a[i].t);

            if((a[i].t-a[i].s)%==)

                a[i].m=a[i].s+(a[i].t-a[i].s)/-;

            else

                a[i].m=a[i].s+(a[i].t-a[i].s)/;

        }

        sort(a,a+n,cmp);

        now=;

        int flag=;

        int cnt=;

        for(i=;i<n;i++)

        {

            if(now>a[i].m)

            {

                flag=;

                break;

            }

            else if(now<=a[i].s)

                now=a[i].s+(a[i].t-a[i].s)/+;

            else if(now>a[i].s)

                now=now+(a[i].t-a[i].s)/+;

            cnt++;

        }

        if(flag)

            printf("NO\n");

        else

        {

            if(cnt==n)

                printf("YES\n");

            else

                printf("NO\n");

        }

    }

    return ;

}