import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        boolean lValid = true;
        boolean lHorizontal = true;
        int lReference;
        int n = in.nextInt();
        List<Pair> lPairs = new ArrayList<Pair>();
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            lPairs.add(new Pair(x, y));
        }
        if (lPairs.get(0).y == lPairs.get(1).y) {
            lHorizontal = false;
            lReference = lPairs.get(0).y;
        } else if (lPairs.get(0).x != lPairs.get(1).x) {
            System.out.println("NO");
            return;
        } else {
            lReference = lPairs.get(0).x;
        }
        for (Pair lPair : lPairs) {
            if (lHorizontal) {
                if (lPair.x != lReference) {
                    lValid = false;
                }
            } else {
                if (lPair.y != lReference) {
                    lValid = false;
                }
            }
        }
        if (lValid) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}

class Pair {
    
    public int x;
    public int y;
    
    public Pair(int pX, int pY) {
        x = pX;
        y = pY;
    }
}