#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    ll n,x,y,c,bx,by,cx,cy,i;
    cin>>n;
    c=n;
    cin>>x>>y;
    bx=x,by=y;
    cx=1,cy=1;
    for(i=1;i<n;i++)
    {
        cin>>x>>y;
        if(x==bx)cx++;
        if(y==by)cy++;
    }
    if(cx==n || cy==n) cout<<"YES\n";
    else cout<<"NO\n";
    return 0;
}