#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;
    cin >> n;
    int x[n],y[n];int l=0;
    for(int a0 = 0; a0 < n; a0++){
            cin >> x[a0] >> y[a0];   
    } for(int a0 = 0; a0 < n-1; a0++){
        if((x[a0]==x[a0+1])||(y[a0]==y[a0+1])) 
            continue;
        else {cout<<"NO"; exit(0);}}
    cout<<"YES";
    return 0;
}