#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 a[20],b[20],x,y,t1=1,t2=1;
    for(int a0 = 0; a0 < n; a0++){
        
        cin >> x >> y;
        a[a0]=x;
        b[a0]=y;
        
    }
    for(int a0 = 0; a0 < n; a0++){
        if(a[a0]!=x)
           t1=-1;
        if(b[a0]!=y)
            t2=-1;
    }
    if(t1*t2==-1)
        cout<<"YES";
    else
        cout<<"NO";
    
    return 0;
}