///Bis-millah-hir-rahmanir-rahim.
//arafat,sylhet engineering college,Bangladesh.

///****Love coding, love solving problems. --Coder shall be coder.******


#include<bits/stdc++.h>
using namespace std;

#define pi acos(-1)
#define nl endl
#define sp " "
#define msa 200010
#define pf printf
#define sc scanf
#define pb push_back
#define pob pop_back

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;


int main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);

    int n,ar[1234],br[1234],ck1=0,ck2=0;
    cin>>n;
    for(int i=0; i<n; i++)  {
        cin>>ar[i]>>br[i];
    }
    for(int i=0; i<n-1; i++) {
        if(ar[i] != ar[i+1]) ck1=1;
        if(br[i] != br[i+1]) ck2=1;
    }
    if(ck1==0 or ck2==0) cout<< "YES" <<nl;
    else cout<< "NO" <<nl;




    return 0;
}