#include<bits/stdc++.h>
#define ll long long

using namespace std;
int main()
{
    ll n,i,j,arr[100],brr[100],flag1=0,flag2=0;
    cin>>n;
    for(i=1;i<=n;i++)
    {
        cin>>arr[i]>>brr[i];
    }
    for(i=2;i<=n;i++)
    {
        if(arr[i]!=arr[i-1])flag1=1;

        if(brr[i]!=brr[i-1]) flag2=1;
    }
    if(!flag1 || !flag2)
        cout<<"YES\n";
    else cout<<"NO\n";
    return 0;
}