#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;
bool same(vector<int> ar)
{
    bool check = false, evenCheck = true, oddCheck = true; 
    for (int even = 2; even < ar.size(); even += 2)
    {
        if (ar[even] != ar[even - 2])
            evenCheck = false;            
    }
    for (int odd = 3; odd < ar.size(); odd += 2)
    {
        if(ar[odd] != ar[odd -2])
            oddCheck = false; 
    }
    if (oddCheck || evenCheck)
        check = true; 
    return check; 
}

int main()
{
    int n;
    cin >> n;
    vector<int> ar;  
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        ar.push_back(x); 
        ar.push_back(y); 
    }
    if(same(ar))
        cout << "YES"; 
    else
        cout << "NO"; 
    return 0;
}