import java.util.*;
import java.io.*;

public class PointsOnARectangle {
    public static InputReader in;
    public static PrintWriter out;
    public static final int MOD = (int) 1e9 + 7;
    public static int[] P, rank;
    public static void main(String[] args) {
	in = new InputReader(System.in);
	out = new PrintWriter(System.out);
	
	int q = in.nextInt();
	while(q-- > 0) {
	    int n = in.nextInt();
	    int[][] p = new int[n][2];
	    P = new int[n];
	    rank = new int[n];
	    for (int i = 0; i < n; i++)     P[i] = i;
	    
	    for (int i = 0; i < n; i++) {
		p[i][0] = in.nextInt();
		p[i][1] = in.nextInt();
	    }
	    
	    for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
		    for (int k = 0; k < n; k++) {
			if(collinear(p[i], p[j], p[k])) {
			    int par = findSet(i);
			    mergeSet(par, j);
			    mergeSet(par, k);
			}
		    }
		}
	    }
	    
	    HashSet<Integer> hs = new HashSet<Integer>();
	    for (int i = 0; i < n; i++) {
		hs.add(findSet(i));
	    }
	    out.println((hs.size() <= 4)? "YES" : "NO");
	}

	out.close();
    }
    
    public static boolean collinear(int[] a, int[] b, int[] c) {
	return ((a[0] == b[0] && b[0] == c[0]) || (a[1] == b[1] && b[1] == c[1]));
    }

    public static int findSet(int x) {
	return P[x] = (P[x] == x ? x : findSet(P[x]));
    }
    
    public static void mergeSet(int x, int y) {
        int px = findSet(x),
                py = findSet(y);
        if(rank[px] > rank[py]) {
            P[py] = px;
        } else {
            P[px] = py;
        }
        if(rank[px] == rank[py]) {
            rank[py]++;
        }
    }
    
    static class Node implements Comparable<Node> {
	int u, v;
	long score;

	public Node(int u, int v) {
	    this.u = u;
	    this.v = v;
	}

	public void print() {
	    System.out.println(u + " " + v + " " + score);
	}

	public int compareTo(Node that) {
	    return Long.compare(this.score, that.score);
	}
    }

    static class InputReader {

	private InputStream stream;
	private byte[] buf = new byte[8192];
	private int curChar, snumChars;
	private SpaceCharFilter filter;

	public InputReader(InputStream stream) {
	    this.stream = stream;
	}

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

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

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

	public int[] nextIntArray(int n) {
	    int a[] = new int[n];
	    for (int i = 0; i < n; i++)
		a[i] = nextInt();
	    return a;
	}

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

	public boolean isSpaceChar(int c) {
	    if (filter != null)
		return filter.isSpaceChar(c);
	    return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	public interface SpaceCharFilter {
	    public boolean isSpaceChar(int ch);
	}
    }
}