#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 vertical = -11, horizontal = -11;
    bool sameLine = true;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if (vertical == -11 && horizontal == -11) {
            vertical = x; horizontal = y;
        } else if (x != vertical && y != horizontal) {
            sameLine = false;
        }
    }
    if (sameLine) {
        cout << "YES";
    } else {
        cout << "NO";
    }
    return 0;
}