#include<bits/stdc++.h>
#define pb(n)   push_back(n)
#define hell     1000000007
#define ll      long long
#define el      endl
#define rn      return
#define fora(a,b,c)     for(int (a)=(b);(a) < (c);(a)++)
#define allinv(it)     for(auto it = v.begin();it!=v.end();it++)
using namespace std;
typedef vector<int> vi;
typedef vector<ll> vli;
typedef vector<vector<ll> > matrix;

int main()
{
    ll n,i,j;
    float m;
    cin >> n;
    ll a[n][2];
    for(i=0;i<n;i++)
        cin >> a[i][0] >> a[i][1];

    for(i=0;i<n-1;i++)
    {
        if (a[i][0] == a[i+1][0])
            continue;
        else
            break;
    }
    if (i == n-1){
    cout << "YES";
    return 0;
    }
    for(i=0;i<n-1;i++)
    {
        if (a[i][1] == a[i+1][1])
            continue;
        else
            break;
    }
    if (i == n-1){
    cout << "YES";
    return 0;
    }
    cout << "NO";
    rn 0;
}