D. Pair Of Lines（ Educational Codeforces Round 41 (Rated for Div. 2)）

 #include <vector>
 #include <iostream>
 #include <algorithm>
 using namespace std;
 typedef long long ll;
 const int N = 1e5 + ;
 ll x[N], y[N];
 int n;

 bool gx(int a, int b, int c, int d)
 {
     return (x[b] - x[a])*(y[d] - y[c]) == (x[d] - x[c])*(y[b] - y[a]);
 }

 int check(int d, int f)
 {
     vector<int>q;
     for (int i = ; i <= n; i++)
     if (!gx(d, f, f, i))
         q.push_back(i);
     if (q.size()<)    return ;
     for (int i = ; i<q.size(); i++)
     if (!gx(q[],q[], q[], q[i]))
         return ;
     return ;
 }

 int main()
 {
     cin >> n;
     for (int i = ; i <= n; i++)
         cin >> x[i] >> y[i];
     if (n< || check(, ) || check(, ) || check(, ))
         cout << "YES" << endl;
     else cout << "NO" <<endl;
     //system("pause");
     return ;
 }