#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=11,Y=11,Xok=1,Yok=1;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(x!=X&&X!=11){
            Xok = 0;
        }
        if(y!=Y&&Y!=11){
            Yok = 0;
        }
        X=x;
        Y=y;
    }
    if(Xok||Yok){
        cout<<"YES";
    }else{
        cout<<"NO";
    }
    return 0;
}