#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int a,b,n;
    //int arr[n];
    //int arrr[n];
    vector<int> myvector;
    vector<int> myvectorr;
    scanf("%d",&n);
    for(int i=0; i<n; i++){
        scanf("%d %d",&a,&b);
        myvector.push_back(a);
        myvectorr.push_back(b);
    }
    if ((adjacent_find( myvector.begin(), myvector.end(),not_equal_to<int>() ) == myvector.end() ) || (adjacent_find( myvectorr.begin(), myvectorr.end(),not_equal_to<int>() ) == myvectorr.end() ))
{
    cout <<"YES"<< endl;
}
else{
    cout<<"NO"<<endl;
}
    return 0;
}