#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <list>
#include <set>
#include <map>

#define lout(x) cout<<x<<endl
#define out(x)  cout<<x
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define forn(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
#define ford(i, n) for (int i = (int)(n) - 1; i >= 0; --i)

typedef long long ll;

using namespace std;

int main() {
    ll T, N, M, X, Y;
    ll i, j, k;
    bool o=true, p=true;

    cin >> T;
    cin >> X >> Y;
    forn(i, T-1) {
        cin >> N >> M;
        if(N!=X) {
            o=false;
        }
        if(M!=Y) {
            p=false;
        }
        if((!o) && (!p)) {
            lout("NO");
            return 0;
        }
    }
    lout("YES");
    return 0;
}