#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,cnt=0,ooo=0;
    vector<int > vp1,vp2;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        vp1.push_back(x);
        vp2.push_back(y);
    }
    for(int i=0;i<n-1;i++){
        if(vp1[i]!=vp1[i+1]){cnt=0;break;}
        else cnt=1;
        
    }
    for(int i=0;i<n-1;i++){
        if(vp2[i]!=vp2[i+1]){ooo=0;break;}
        else ooo=1;
    }
    int k=max(cnt,ooo);
    if(k==1)cout<<"YES"<<endl;
    else cout<<"NO";
    return 0;
}