#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 a[100][100];
    int x;
    int y;
    scanf("%d",&n);
    for(int i = 0; i < n; i++){
        
        scanf("%d %d",&x,&y);
        
        a[i][0] = x;
        a[i][1] = y;    
    }
    int count=1;
    int key1 = a[0][0];
    int key2 = a[0][1];
    for(int i = 1 ; i < n ; i ++) {
        if((a[i][0] != key1) && (a[i][1] != key2)) {
            printf("NO\n");
            count = 0;
            break;
        }
    }    
    if(count) {
        printf("YES\n");
    }
    
    
    return 0;
}