#include<bits/stdc++.h>
using namespace std;
#define sld(x) scanf("%lld",&x)
#define sy(x) scanf("%x",&y)
#define pb push_back
#define ll long long
#define mp make_pair
#define fi first
#define se second
#define pii pair<int,int>
#define all(c) c.begin(),c.end()
#define mini(c) min_element(all(c))
#define maxi(c) max_element(all(c))
#define mod 1000000007LL
ll powmod(ll a,ll b) {ll res=1;a%=mod;for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}

int main(){
    ll n,i,a[1000],b[1000],p,q,count=0,count2=0;
    cin>>n;
    for(i=0;i<n;i++){
        cin>>a[i]>>b[i];
    }
    p=a[0];
    q=b[0];
    for(i=0;i<n;i++){
        if(a[i]==p){
            count++;
        }
        if(b[i]==q){
            count2++;
        }
    }
    if(count==n||count2==n){
        cout<<"YES";
    }
    else{
        cout<<"NO";
    }



}