#include<iostream>
#include<cstdio>
using namespace std;

int main()
{
    int n;
    int x1,y1,x2,y2;
    int data[13];
    int flag1 = 0;
    int flag2 = 0;

    scanf("%d",&n);
    scanf("%d %d",&x1,&y1);

    for(int i=0;i<n-1;i++)
    {
        scanf("%d %d",&x2,&y2);
        if(x1 > x2 || x1 < x2) flag1++;
        if(y1 > y2 || y1 < y2) flag2++;
    }
    if(flag1 == 0 || flag2 == 0)
        printf("YES\n");
    else
        printf("NO\n");
    return 0;
}