#include <iostream>
#include <fstream>
#include <list>
#include <stack>
#include <deque>
#include <utility>
#include <queue>
#include <set>
#include <map>
#include <bitset>
#include <vector>
#include <cmath>
#include <string>
#include <algorithm>
#include <iomanip>
#include <ctime>
#include <iterator>
#include <cstdio>
#include <cstring>
#include <cstdlib>


using namespace std;

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

#define f first
#define s second
#define pb push_back
#define mp make_pair

const int maxn = 100500;
const int inf = 2e9;
const double eps = 1e-8;
const int base = 1073676287;

int a[maxn];
int b[maxn];

int main()
{
    srand( time( 0 ) );
    // freopen( "input.txt", "r", stdin );
    // freopen( "output.txt", "w", stdout );
    // ios_base::sync_with_stdio(false);
    int n;
    scanf ( "%d", &n );
    for ( int j = 0; j < n; j++ )
    	scanf ( "%d%d", &a[j], &b[j] );
    bool cor = false;
    bool cor1 = true;
    for ( int j = 1; j < n; j++ )
    	if ( a[j - 1] != a[j] )
    		cor1 = false;
    cor = max( cor, cor1 );
    cor1 = true;
    for ( int j = 1; j < n; j++ )
    	if ( b[j - 1] != b[j] )
    		cor1 = false;
    cor = max( cor, cor1 );
    if ( cor )
    	puts( "YES" );
    else
    	puts( "NO" );
    return 0;
}