#include <bits/stdc++.h>
#include <unordered_map>
using namespace std;
typedef long long LL;
#define mp make_pair
#define CHECK(x) if(!(x)) return false;
#define CHECKRET(x, y) if(!(x)) return (y);
#define SKIP(x) if((x)) continue;
typedef pair<int, int> pii;

#ifdef INFOARENA
#define ProblemName "trapez"
#else
#define ProblemName "fis"
#endif

#define InFile ProblemName ".in"
#define OuFile ProblemName ".out"

const int MAXBUF = 30000000;
char parseBuf[MAXBUF];
char *head;
bool isDigit[255];

void parseInit() {
  int a = fread(parseBuf, 1, MAXBUF, stdin);
  parseBuf[a] = 0;
  head = parseBuf;
  memset(isDigit, 0, sizeof isDigit);
  for (int i = '0'; i <= '9'; ++i)
    isDigit[i] = true;
}

int nextInt() {
  int ans = 0;
  for (; !isDigit[*head]; ++head);
  for (; isDigit[*head]; ++head)
    ans = ans * 10 + (*head) - '0';
  return ans;
}

const int MAXN = 1010;
pii v[MAXN];
int N;

LL hsh(int x, int y) {
  if (x == 0)
    y = 1;
  else if (y == 0)
    x = 1;
  else {
    int g = __gcd(x, y);
    x /= g;
    y /= g;
  }
  return 1LL * x * INT_MAX + y;
}

unordered_map<LL, int> pantaFreq;

int main() {
  assert(freopen(InFile, "r", stdin));
  assert(freopen(OuFile, "w", stdout));
  parseInit();
  N = nextInt();
  for (int i = 0; i < N; ++i) {
    v[i].first = nextInt(), v[i].second = nextInt();
    for (int j = i - 1; j >= 0; --j)
      ++pantaFreq[hsh(v[j].second - v[i].second,
        v[j].first - v[i].first)];
  }
  int ans = 0;
  for (const auto &it : pantaFreq)
    ans += it.second * (it.second - 1) / 2;
  printf("%d\n", ans);
  return 0;
}