#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;

vector<int> a[100005];
vector<int> b[100005];
int main(){
    int n, x1, y1;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        x += 10;
        y += 10;
        x1 = x;
        y1 = y;
        a[x].push_back(y);
        b[y].push_back(x);
    }
    if(a[x1].size() == n) {
        cout << "YES";
        return 0;
    }
    if(b[y1].size() == n) {
        cout << "YES";
        return 0;
    }
    cout << "NO";
    return 0;
}