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

int main() {
    int n;
    cin >> n;
    vector<int> x(n), y(n);
    int ans = 0;
    for (int i=0; i<n; i++) cin >> x[i] >> y[i];
    for (int i=0; i<n; i++) {
        for (int j=0; j<n; j++) {
            if (i==j) continue;
            int dx = x[i] - x[j];
            int dy = y[i] - y[j];
            if (-dx <= dy && dy <= dx) ans++;
        }
    }
    cout << ans << endl;
}
#include <vector>
#include <iostream>
using namespace std;
int main(){
  int N;
  cin >> N;
  int a=0;
  vector<double> X(N,0);
  vector<double> Y(N,0);
  for (int i=0; i<N; i++){
    cin >> X[i] >> Y[i];
  }
  for (int i=0; i<N; i++){
    for (int j=i+1; j<N; j++){
      for (int k=j+1; k<N; k++){
        if (X[i]==X[j] && X[i]==X[k]){
          a=1;
        }
        else {
          double d1=(Y[j]-Y[i])/(X[j]-X[i]);
          double d2=(Y[k]-Y[i])/(X[k]-X[i]);
          if (d1==d2){
            a=1;
            break;
          }
        }
      }
      if (a==1){
        break;
      }
    }
    if (a==1){
        break;
    }
  }
  if (a==0){
    cout << "No" <<endl;
  }
  else {
    cout << "Yes" <<endl;
  }
}
  