#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

struct a{
    int x;
    int y;
    
}li[100];

int main(){
    int n;
    cin >> n;
   
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >>li[a0].x >>li[a0].y;
        
    }
    
    int i;
    
    int flagx=0;
    int flagy=0;
    for (i=1;i<n && (!flagx || !flagy);i++){
      // int s = (li[i].y - li[i-1].y) *li[i-2].x  + (li[i-1].x - li[i].x) * li[i-2].y + (li[i].x * li[i-1].y - li[i-1].x * li[i].y);
   if(li[i].y!=li[i-1].y)
       flagy=1;
       if(li[i].x!=li[i-1].x)
       flagx=1;
        if(flagx && flagy)
            break;
       
    }
    
    if(i==n)
        cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return 0;
}