#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,prevX;
    int y,prevY;
    cin >> x >> y;
    prevX=x;prevY=y;
    for(int a0 = 1; a0 < n; a0++){
        if(prevX !=x && prevY!=y){
            cout << "NO"<<endl;
            return 0; 
        }else{
            prevX=x;prevY=y;            
        }
        cin >> x >> y;
    }
    cout<<"YES"<<endl;
    return 0;
}