#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,flag = 0;
    cin >> n;
    int a[n],b[n];
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        a[a0] = x;
        b[a0] = y;
        
    }
    for(int a0 = 1; a0 < n; a0++)
        {
            if(a[a0 - 1] != a[a0] && b[a0 - 1] != b[a0])
                flag = 1;
        }
    
        if(flag == 1)
            cout << "NO";
        else
            cout << "YES";
    return 0;
}