#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,fl1=1,fl2=1,x,y,a,b;
    cin >> n;
    cin>>a>>b;
    for(int a0 = 1; a0 < n; a0++){
        cin >> x >> y;
        if(x!=a)
            fl1=0;
        if(y!=b)
            fl2=0;
    }
    if(fl1 || fl2)
        cout<<"YES\n";
    else
        cout<<"NO\n";
    return 0;
}