#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 xy[3][2] = {{-20,-20}, {-20,-20}, {-20,-20} };
    int x1, y1;
    string ans = "YES";
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(a0 < 1){
            x1 = x;
            y1 = y;
        }
        else{
            if(x1 != x && x1 != -20)
                x1 = -20;
            if(y1 != y && y1 != -20)
                y1 = -20;
        }
        
        if(x1 == -20 && y1 == -20){
            ans = "NO";
            break;
        }
               
    }
    cout << ans;
    return 0;
}