#include<bits/stdc++.h>
using namespace std;

#define PB push_back
#define MP make_pair
#define ll long long
#define ff first
#define ss second
#define MAX 200005

typedef pair<ll, ll> PII;
vector<PII> vv;
vector<ll> v, v1;
set<ll> st;
ll i,j,n,m,ans,mx=-1,mn,sm,p,q,k,r;
ll ar[MAX], br[MAX];
string s;
bool flg= true;
char ch;



int main()
{
    cin >> n;
    for(i=0; i<n; i++)
    {
        cin >> ar[i] >> br[i];
    }
    int cnt1=0, cnt2=0;
    for(i=0; i<n-1; i++)
    {
        if(ar[i]==ar[i+1])
            cnt1++;
    }
    for(i=0; i<n-1; i++)
    {
        if(br[i]==br[i+1])
            cnt2++;
    }
    if(cnt1==n-1||cnt2==n-1)
        cout<<"YES"<<endl;
    else
        cout<<"NO"<<endl;
    return 0;
}