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

typedef pair<int, int> pii;
typedef long long ll;
typedef vector<int> vi;

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define rep(i,n) rep2(i,0,n)
#define rep2(i,m,n) for(int i=m;i<(n);i++)
#define ALL(c) (c).begin(),(c).end()

int n;
int x[12], y[12];
bool f = 0;

int main() {
    cin >> n;
    rep(i, n) cin >> x[i] >> y[i];

    for (int i = -10; i <= 10; ++i) {
	bool p = 1, q = 1;
	rep(j, n) {
	    if (x[j] != i) p = 0;
	    if (y[j] != i) q = 0;
	}
	f |= p;
	f |= q;
    }
    puts(f ? "YES" : "NO");

    return 0;
}