#include <iostream>

using namespace std;

int main() {
	int t;
	cin >> t;
	while(t--){
	    int n, l = 0, r = 32;
	    cin >> n;
	    for (int i = 0; i < n; i++) {
	        int a, b;
	        cin >> a >> b;
	        l = max(l, a);
	        r = min(r, b);
	    }
	    cout << (l > r ? "NO" : "YES") << endl;
	}
    return 0;
}