#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,i,j,k,l;
    cin >> n;
    int a[100000],b[100000];
    for(int a0 = 0; a0 < n; a0++){
        cin>>a[a0]>>b[a0];
    }
    for(i=1;i<n;i++)
        if(a[i]==a[i-1]){continue;}
    else{break;}
    for(j=1;j<n;j++)
        if(b[j]==b[j-1]){continue;}
    else{break;}
    if(i==n || j==n){cout<<"YES\n";}
    else{cout<<"NO\n";}
    return 0;
}