#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n,x,y,temp1,temp2,c1=0,c2=0;
    cin >> n;
    cin>>x>>y;
    temp1=x;
    c1++;
    temp2=y;
    c2++;
    for(int i = 1; i < n; i++){
        
        cin >> x >> y;
        if(temp1==x)
            c1++;
        if(temp2==y)
            c2++;
    }
    if(c1==n||c2==n)
        cout<<"YES"<<endl;
    else
        cout<<"NO"<<endl;
    return 0;
}