#include <bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	bool x = true;
	bool y = true;
	int a,b,pa,pb;
	scanf("%d",&n);
	scanf("%d %d",&a,&b);
	pa = a;
	pb = b;
	for(int i=1;i<n;i++)
	{
		scanf("%d %d",&a,&b);
		if(a!=pa)
			x = false;
		if(b!=pb)
			y = false;
		pa = a;
		pb = b;
	}
	if(x||y)
		printf("YES\n");
	else printf("NO\n");
}