#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MP make_pair
#define PB push_back
#define f first
#define s second
ll n,m;
#define MAX 1000000000000000001
const int MOD = 1e9 + 7;
ll gcd(ll a , ll b )
{
    if(!b) return a;
    return gcd(b,a%b);
}
ll power(ll a ,ll b)
{
    if(!b) return 1;
    ll temp = (power(a,b/2))%MOD;

    if(b&1)
        return (((temp*temp)%MOD)*b)%MOD;

    else
        return (temp*temp)%MOD;
}

int main()
{
    int n,a,b,flag=0,val1,val2,count=1;
    cin>>n;
    int x[n],y[n];
    for(int i=0;i<n;i++)
        cin>>x[i]>>y[i];

    for(int i=1;i<n;i++)
    {
        if(x[i]==x[i-1]) count++;
    }
    if(count!=n)
    {
        count=1;
        for(int i=1;i<n;i++)
            if(y[i]==y[i-1]) count++;
    }
    if(count==n)cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return 0;
}