#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; cin.ignore();
    int x[n], y[n];
    for(int a0 = 0; a0 < n; a0++){
        cin >> x[a0]; cin >> y[a0];
        
        if(a0 < n-1)
            cin.ignore();
    }
    
    bool b1 = false, b2 = false;
    for(int i=0; i<n-1; i++){
        if(x[i] != x[i+1] && !b1)
            b1 = true;
        
        if(y[i] != y[i+1] && !b2)
            b2 = true;
    }
    
    if(!b1 || !b2)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
    
    return 0;
}