#include <bits/stdc++.h>

using namespace std;
int main()
{
    int n,ara1[50],ara2[50];
    scanf("%d",&n);
    for(int i = 0; i < n; i++){
        scanf("%d%d",&ara1[i],&ara2[i]);
    }
    int flag1 = 0, flag2 = 0;
    for(int i = 0; i <= n-1; i++){
        if(ara1[i] == ara1[i+1]){
            flag1++;
        }
        else if(ara2[i] == ara2[i+1]){
            flag2++;
        }
    }
    if(flag1 == n-1){
        printf("YES\n");
    }
    else if(flag2 == n-1){
        printf("YES\n");
    }
    else{
        printf("NO\n");
    }
    return 0;
}