/*

-------------------------------------------------------------------------------------------------\
 \       |AUTHOR: RAGHU PAAVAN(rap)  :D ---------------------------------------------------------- \
 /       |        NIT CALICUT  ------------------------------------------------------------------- /
---------|----------------------------------------------------------------------------------------/

*/
#include<bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define ll    long long int
#define all(c) c.begin(),c.end()
#define tr(c,i) for(typeof((c).begin()) i = (c).begin(); i != (c).end(); i++)
#define scan(x) scanf("%d", &x)
#define scanl(x) scanf("%lld", &x)
#define print(a) printf("%d\n",a)
#define printl(a) printf("%lld\n",a)
#define pb push_back
#define maxn 100005
ll a[maxn];
ll b[maxn];
int main()
{
    ll i,j,k,n,t;
    cin>>n;
    for(i=0;i<n;i++)
    {
        cin>>a[i]>>b[i];
    }
    for(i=1;i<n;i++)
    {
        if(a[i]!=a[i-1])break;
    }
    if(i==n)goto hell;
    for(i=1;i<n;i++)
    {
        if(b[i]!=b[i-1])break;
    }
    if(i==n)
    {
        hell:
        cout<<"YES\n";
        return 0;
    }
    cout<<"NO\n";
    return 0;
}