#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;


int main(){
    int n,x[10],y[10],flag=0;
    cin >> n;
    for(int i = 0; i < n; i++){
        cin >> x[i] >> y[i];
    }
    for(int i=1;i<n-1;i++)
        {
        if((x[i]-x[i-1])!=0)
            {
        (y[i]-y[i-1])/(x[i]-x[i-1])!=(y[i+1]-y[i])/(x[i+1]-x[i]);
            flag=1;
        break;
        }}
    if(flag==1)
        cout<<"NO";
    else
        cout<<"YES";
    return 0;
}