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


int main() {
    int n,j,k,x,y;
    cin>>n;
    int arr[100]={0};
    int mmax= 0;
    int t=n;
    map<int,int> xc,yc;
    while(n--)
        {
        cin>>x>>y;
        xc[x]++;
        yc[y]++;
        mmax=(mmax,max(xc[x],yc[y]));
       }
    if(mmax==t)
        cout<<"YES";
    else
        cout<<"NO";
    return 0;
}