#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,c=0;
    cin >> n;
    int x[10],y[10];
    for(int i = 0; i< n; i++){
        
        cin >> x[i]; cin >> y[i];
    }
    for (int j=1; j<n; j++)
    {
        if(y[j]!=y[j-1])
            if(x[j]!=x[j-1])
            c++;
    }
    if(c>0)
        cout<<"NO";
    else cout<<"YES";
    return 0;
}