#include <bits/stdc++.h>
using namespace std;

int main() {
    int t, n, c, d;
    scanf("%d", &t);
    while (t--) {
        scanf("%d", &n);
        bool contains = false;
        set<int> cur;
        set<pair<int, int>> tiles;
        while (n--) {
            scanf("%d%d", &c, &d);
            tiles.emplace(c, d);
            int k = c + d;
            if (!k) contains = true;
            if (c == 0 || d == 0) continue;
            while (cur.count(k)) {
                cur.erase(k);
                k--;
            }
            cur.insert(k);
        }
        if (!contains) {
            printf("YES\n");
            continue;
        }
        vector<int> v(cur.begin(), cur.end());
        int a = 0, b = 0;
        while (tiles.count({0, a})) a++;
        while (tiles.count({b, 0})) b++;
        if (a > b) swap(a, b);
        if (v.empty()) printf("YES\n");
        else if (a == b) {
            a--;
            if (v[0] > a) printf("YES\n");
            else printf("NO\n");
        }
        else if (v[0] > a || (v[0] == a && (v.size() == 1 || v[1] > b))) printf("YES\n");
        else printf("NO\n");
    }
}