/*------------------------------------------------------------- \
  |                                                             |
  |     VIKRAM SINGH DHINWAL 
  |     ABV-IIITM,GWALIOR, M.P                                  |
  |                                                             |
  ---------------------------------------------------------------*/
#include<bits/stdc++.h>
using namespace std;
#define   FOR(i,a,b)        for(i=a;i<b;i++)
#define   RFOR(i,a,b)       for(i=a;i>=b;i--)
#define   AFOR(i,a,b)       for(i=a;i<=b;i++)
#define   max(a,b)          (a>b?a:b)
#define   min(a,b)          (a<b?a:b)
#define   ll                long long int 
#define   pb                push_back
#define   mp                make_pair
#define   f                 first
#define   s                 second
#define   mod               1000000007
#define   clr(a)            memset(a,0,sizeof(a))
#define   abs(x)            ( (x)>0?(x):(-(x)) )
#define   ub(X,v)           upper_bound(X.begin(),X.end(),v)
#define   lb(X,v)           lower_bound(X.begin(),X.end(),v)
#define   pie               3.1415926536
#define   inf               1e9
#define   FASTER            std::ios::sync_with_stdio(false)
typedef pair< int ,int > PP;
typedef map< char ,int > MM;
typedef vector<int> V;
int gcd(int a,int b){ return b?gcd(b,a%b):a; }
int main()
{
    int n,cnt1=0,cnt2=0,a[11],b[11],x,y,i;
    cin>>n;
    FOR(i,0,n)
    {
        cin>>a[i]>>b[i];
    }
    x=a[0],y=b[0];
    FOR(i,0,n)
    {
       if(a[i]==x) cnt1++;
       if(b[i]==y) cnt2++;
    }
    if(cnt1==n || cnt2==n)
     cout<<"YES\n";
    else
     cout<<"NO\n";
}