#include<stdio.h>


struct point {
    int x;
    int y;


};


int main()
{
    int n,t,i,j,m,flag;
    scanf("%d",&n);
    struct point p[n];
    for (i=0;i<n;i++){
        scanf("%d %d",&p[i].x,&p[i].y);

    }
     m=p[0].x;
        t=p[0].y;
    for (i=0;i<n;i++){
        if (p[i].x==m||p[i].y==t){
            flag=1;
        }
        else {
            flag=0;
            break;
        }
    }
    if (flag==1){
        printf("YES");

    }
    else {
        printf("NO");
    }
    return 0;
}