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); int n = in.nextInt(); int a=in.nextInt(); int b=in.nextInt(); boolean sameV=true; boolean sameH=true; for(int a0 = 1; a0 < n; a0++){ int x = in.nextInt(); int y = in.nextInt(); if(x!=a) sameV=false; if(y!=b) sameH=false; } if(sameV||sameH) System.out.print("YES"); else System.out.print("NO"); } }