#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;

stack<int>s1;
stack<int>s2;
int main(){
    int n;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(s1.empty() || x==s1.top())
            {
            s1.push(x);}
        if(s2.empty() || y==s2.top()){
        s2.push(y);
        }
        }
    if(s1.size()==n ||s2.size()==n)
        {
        cout<<"YES";
    }
    else
        cout<<"NO";
    return 0;
}