#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;
    int status = 0;
    cin >> n;
    int lastx;
    int lasty;
    bool flag = true;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(a0 == 0) {
            lastx = x;
            lasty = y;
        }
        else {
            if(flag && status==0) {
                if(lastx == x) {
                    status |= 1;
                }
                if(lasty == y){
                    status |= 2;
                }
                flag = false;
            }
            if((status&1) && (lastx != x))
                    status &= 2;
            if((status&2) && (lasty != y))
                    status &= 1;
        }
    }
    if(status)
        cout << "YES\n";
    else
        cout << "NO\n";
    return 0;
}