import java.io.IOException;
import java.util.InputMismatchException;

public class PointsOnARectangle {
	private static final int INF = 1000000;
	
    public static void main(String[] args) {
        FasterScanner sc = new FasterScanner();
        
        int Q = sc.nextInt();
        
        StringBuilder sb = new StringBuilder();
        
        outer:
        for (int q = 0; q < Q; q++) {
        	int N = sc.nextInt();
        	int[] X = new int[N];
        	int[] Y = new int[N];
        	int left = INF;
        	int rite = -INF;
        	int bot = INF;
        	int top = -INF;
        	for(int i = 0; i < N; i++) {
        		X[i] = sc.nextInt();
        		Y[i] = sc.nextInt();
        		left = Math.min(left, X[i]);
        		rite = Math.max(rite, X[i]);
        		bot = Math.min(bot, Y[i]);
        		top = Math.max(top, Y[i]);
        	}
        	for (int i = 0; i < N; i++) {
        		if (X[i] != left && X[i] != rite && Y[i] != bot && Y[i] != top) {
        			sb.append("NO\n");
        			continue outer;
        		}
        	}
        	sb.append("YES\n");
        }
        
        System.out.print(sb.toString());
    }
    
	public static class FasterScanner {
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = System.in.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
	        
	    public int[] nextIntArray(int n) {
	        int[] arr = new int[n];
	        for (int i = 0; i < n; i++) {
	            arr[i] = nextInt();
	        }
	        return arr;
	    }
        
		public long[] nextLongArray(int n) {
		    long[] arr = new long[n];
		    for (int i = 0; i < n; i++) {
		        arr[i] = nextLong();
		    }
		    return arr;
		}

	    private boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}
	}
}