#include <bits/stdc++.h>
 
using namespace std;
 
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define RFOR(i, b, a) for(int i = (b) - 1; i >= (a); --i)
#define REP(i, N) FOR(i, 0, N)
#define RREP(i, N) RFOR(i, N, 0)
#define FILL(A,value) memset(A,value,sizeof(A))
 
#define all(V) V.begin(), V.end()
#define sz(V) (int)V.size()
#define pb push_back
#define mp make_pair
#define Pi 3.14159265358979
 
#define pp(a) cout<<a[i].first<<" "<<a[i].second<<"\n";
 
typedef unsigned long long ll;
typedef unsigned long long llu;
typedef vector <ll> vi;
typedef long double ld;
typedef pair <ll, ll> pii;
 
inline ld gett() { return ld(clock()) / CLOCKS_PER_SEC; }
 
const ll MOD = 1000000007;

void solve()
{
	int n,x,y,p,q;
    cin>>n;
    cin>>x>>y;
    int f=0;
    FOR(i,0,n-1)
    {
        cin>>p>>q;
        if(p!=x && q!=y){f=1;break;}
    }
    if(f==0)cout<<"YES";
    else cout<<"NO";
}
 
int main() 
{
	ios::sync_with_stdio(false);cin.tie(0);
 
	ld stime = gett();
 
	solve();
 
	cerr << "Time: "<< gett() - stime << endl;
 
	return 0;
}