import java.io.*; import java.util.*; import java.math.BigInteger; import java.util.Map.Entry; import static java.lang.Math.*; public class Solution extends PrintWriter { void run() { int n = nextInt(); int x = nextInt(), y = nextInt(); boolean h = true, v = true; for (int i = 1; i < n; i++) { h &= nextInt() == x; v &= nextInt() == y; } if (h | v) { println("YES"); } else { println("NO"); } } int[][] nextMatrix(int n, int m) { int[][] matrix = new int[n][m]; for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) matrix[i][j] = nextInt(); return matrix; } String next() { while (!tokenizer.hasMoreTokens()) tokenizer = new StringTokenizer(nextLine()); return tokenizer.nextToken(); } boolean hasNext() { while (!tokenizer.hasMoreTokens()) { String line = nextLine(); if (line == null) { return false; } tokenizer = new StringTokenizer(line); } return true; } int[] nextArray(int n) { int[] array = new int[n]; for (int i = 0; i < n; i++) { array[i] = nextInt(); } return array; } int nextInt() { return Integer.parseInt(next()); } long nextLong() { return Long.parseLong(next()); } double nextDouble() { return Double.parseDouble(next()); } String nextLine() { try { return reader.readLine(); } catch (IOException err) { return null; } } public Solution(OutputStream outputStream) { super(outputStream); } static BufferedReader reader; static StringTokenizer tokenizer = new StringTokenizer(""); static Random rnd = new Random(); public static void main(String[] args) throws IOException { reader = new BufferedReader(new InputStreamReader(System.in)); Solution solution = new Solution(System.out); solution.run(); solution.close(); reader.close(); } }