#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,x,y,p[11],q[11],i;
    cin >> n;
    //cin>>x>>y;
    for(int a0 = 0; a0 < n; a0++){
        cin>>p[a0]>>q[a0];
    }
    for(i=1;i<n;i++){
        if(p[i]==p[i-1])continue;
        else break;
    }
    if(i==n){
        cout<<"YES";
        return 0;
    }
    for(i=1;i<n;i++){
        if(q[i]==q[i-1])continue;
        else break;
    }
    if(i==n){
        cout<<"YES";
        return 0;
    }
    cout<<"NO";
    return 0;
}