#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,c1=0,x,y,f=0,f1=0;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
       
        c=x;
        c1=y;
        cin >> x >> y;
        if(a0!=0){
        if(c!=x)
            f=1;
        if(c1!=y)
            f1=1;}
    }
    if(f==0||f1==0)
         cout<<"YES\n";
    else
       cout<<"NO\n";
    return 0;
}