#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;
    bool flag=1;
    cin >> n;
    int a[n],b[n];
    for(i = 0; i < n; i++)
        cin >> a[i] >> b[i];
    for(i=1;i<n;i++)
        if(a[i]!=a[i-1])    break;
    if(i==n)  {cout<<"YES\n";return 0;}
    for(j=1;j<n;j++)
        if(b[j]!=b[j-1])    break;
    if(j==n)    cout<<"YES\n";
    else  cout<<"NO\n";
    return 0;
}