#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 x, x2;
    int y, y2;
    cin >> x >> y;
    bool equalX = false, equalY = false;
    for(int a0 = 1; a0 < n; a0++) {
        cin >> x2 >> y2;
        if (x2 == x and y2 == y)
            continue;
        else if (x2 != x and y2 != y) {
            cout << "NO\n";
            return 0;
        } else {
            if (not equalX and not equalY) {
                if (x2 == x) {
                    equalX = true;
                } else if (y2 == y) {
                    equalY = true;
                }
            } else if (equalX and x != x2) {
                cout << "NO\n";
                return 0;
            } else if (equalY and y != y2) {
                cout << "NO\n";
                return 0;
            }
        }
    }
    cout << "YES\n";
    return 0;
}