//__ hr1212 __//

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef map<int,int> mi;

#define si(a) scanf("%d",&a)
#define sii(a,b) scanf("%d %d",&a,&b)
#define siii(a,b,c) scanf("%d %d %d",&a,&b,&c)
#define pi(a) printf("%d\n",a)
#define nl printf("\n");
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define f(i,a,b) for(i=a;i<b;i++)
#define rf(i,a,b) for(i=a;i>=b;i--)
#define clr(x,a) memset(x,a,sizeof(x))
#define MAX 1000100
#define MOD 1000000007

int n,m,a[MAX],b[MAX];

int main(){
    int r,k,i,c=0,x=1,y=1,j,t,l,z,x1=0,y1=0;
    ll ans=0;string p;

    si(n);
    f(i,0,n){
		sii(a[i],b[i]);
	}
    f(i,1,n){
    	if(a[i]==a[i-1])
    		x++;
    	if(b[i]==b[i-1])
    		y++;
    }
    if(x==n || y==n)
    	cout<<"YES";
    	else
    	cout<<"NO";
    	nl;
    return 0;
}