#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,prev_x=0,prev_y=0,x,y;
    bool X = false, Y=false;
    cin >> n;
    cin >> x >> y;
        prev_x=x;
        prev_y=y;
    for(int a0 = 1; a0 < n; a0++){
        cin >> x >> y;
        if(x!=prev_x)
            {
            prev_x=x;
            X=true;
        }
        if(y!=prev_y)
            {
            prev_y=y;
            Y=true;
        }
        
        
    }
    if(X & Y){
        cout<<"NO\n";
    }
    else
        cout<<"YES\n";
    
    
    
    return 0;
}