#include <iostream>
#include <algorithm>
#include <cmath>


using namespace std;

int n;

struct node
{
    int s,e,mid;
}a[100005];

bool cmp(node a,node b)
{
    return a.mid < b.mid;
}

int main()
{
    while(cin >> n && n)
    for(int i = 0;i < n;i++)
    {
        cin >> a[i].s >> a[i].e;
        a[i].mid = a[i].e - ((a[i].e - a[i].s) / 2 + 1);
    }
    sort(a,a+n,cmp);

    int MIN = 0;
    for(int i = 0;i < n;i++)
    {
        if(MIN > a[i].mid)
        {
            cout << "NO" << endl;
        }
        else
        {
            MIN = max(MIN,a[i].s);
            MIN += (a[i].e - a[i].s) / 2 + 1;
        }
    }

    return 0;
}