#include<bits/stdc++.h>
using namespace std;

int main(){
    int n,i,x,y,temx,temy,count1=0,count2=0;
    scanf("%d",&n);
    scanf("%d%d",&temx,&temy);
    for(i=0;i<n-1;i++){
        scanf("%d%d",&x,&y);
        if(temx==x){
            count1++;
        }
        if(temy==y){
            count2++;
        }
        temx=x,temy=y;
    }
    if(count1==n-1||count2==n-1)printf("YES\n");
    else printf("NO\n");
    return 0;
}