#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;
bool checkLineVer(int x, int y, int z, int a, int check){
    if(x == z && x == check){
        return true;
    }
    return false;
}

bool checkLineHor(int x, int y, int z, int a, int check){
    if(y == a && y == check){
         return true;   
    }
    return false;
}

int main(){
    int n;
    cin >> n;
    int a, b;
    a = b =0;
    bool ver = false;
    bool check = false;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
         
        cin >> x >> y;
        if(a0 != 0){
            if(check == false)
                break;
           
            if(ver == true)
              check =  checkLineVer(x, y, a, b, x);  
           else
              check = checkLineHor(x, y, a, b, x); 
        }
        a = x;
        b = y;
        if(a0 == 0){
            check = checkLineVer(x, y, a, b, x);
           if(check == true)
               ver = true;
           else{
              check = checkLineHor(x, y, a, b, x) ;
            }
        }
    }
    if(check == true)
        cout << "YES";
    else
        cout << "NO";
    return 0;
}