#include <cstdio>
#include <stack>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <functional>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <string>
#include <map>
#include <iomanip>
#include <cmath>
#define LL long long
#define ULL unsigned long long
#define SZ(x) (int)x.size()
#define Lowbit(x) ((x) & (-x))
#define MP(a, b) make_pair(a, b)
#define MS(arr, num) memset(arr, num, sizeof(arr))
#define PB push_back
#define F first
#define S second
#define ROP freopen("input.txt", "r", stdin);
#define MID(a, b) (a + ((b - a) >> 1))
#define LC rt << 1, l, mid
#define RC rt << 1|1, mid + 1, r
#define LRT rt << 1
#define RRT rt << 1|1
#define BitCount(x) __builtin_popcount(x)
#define BitCountll(x) __builtin_popcountll(x)
#define LeftPos(x) 32 - __builtin_clz(x) - 1
#define LeftPosll(x) 64 - __builtin_clzll(x) - 1
const double PI = acos(-1.0);
const int INF = 0x3f3f3f3f;
using namespace std;
const double eps = 1e-6;
const int MAXN = 1e5 + 10;
const int MOD = 1000007;
typedef pair<int, int> pii;
typedef vector<int>::iterator viti;
typedef vector<pii>::iterator vitii;
 
struct POINT
{
    int st, ed, mid;
    bool operator < (const POINT &a) const
    {
        if (mid != a.mid) return mid < a.mid;
        return st < a.st;
    }
}pit[MAXN];
 
int main()
{
    //ROP;
    int n, i, j;
    while (scanf("%d", &n), n)
    {
        for (i = 0; i < n; i++)
        {
            scanf("%d%d", &pit[i].st, &pit[i].ed);
            pit[i].mid = pit[i].st + (pit[i].ed - pit[i].st) / 2 + 1;
        }
        sort(pit, pit + n);
        int curTime = 0;
        for (i = 0; i < n; i++)
        {
            if (curTime >= pit[i].mid) break;
            curTime = max(curTime, pit[i].st);
            curTime += pit[i].mid - pit[i].st;
        }
        printf("%s\n", i == n ? "YES" : "NO");
    }
    return 0;
}