#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n;
    cin >> n;
    int firstX, firstY;
    cin >> firstX >> firstY;
    int same = -2; // 0 - x; 1 - y
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if (same == -2)
        {
            if (x == firstX && y == firstY)
                continue;
            
            if (x == firstX)
                same = 0;
            else if (y == firstY)
                same = 1;
            else
            {
                same = -1;
                break;
            }
        }
        else 
        {
            if (same == 0)
            {
                if (x != firstX)
                {
                    same = -1;
                    break;
                }
            }
            else if (same == 1)
            {
                if (y != firstY)
                {
                    same = -1;
                    break;
                }
            }
        }
    }
    if (same == -1)
        cout << "NO" << endl;
    else
        cout << "YES" << endl;
    return 0;
}