#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;
    vector<int> x_vec;
    vector<int> y_vec;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        x_vec.push_back(x);
        y_vec.push_back(y);
    }
    
    bool x = 1, y = 1;
    for (int i=0; i<n-1; i++) {
        bool temp1, temp2;
        temp1 = (x_vec[i] == x_vec[i+1]);
        temp2 = (y_vec[i] == y_vec[i+1]);
        x = x&temp1;
        y = y&temp2;
    }

    
    if (x|y == 1) cout << "YES";
    else cout << "NO";
    
    return 0;
}