#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;
    vector<int> v,v1;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        v.push_back(x);
        v1.push_back(y);
    }
    int cnt=0;
    int cnt1=0;
    for(int i=0;i<v.size()-1;i++)
        {
        if(v[i]==v[i+1])
            cnt++;
       else
           break;
    }
    for(int j=0;j<v1.size()-1;j++)
        {
         if(v1[j]==v1[j+1])
            cnt1++;
        else
            break;
    }
  //  cout<<cnt<<" "<<cnt1;
    if(cnt==v.size()-1||cnt1==v1.size()-1)
        cout<<"YES";
    else
        cout<<"NO";
    return 0;
}