#include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
using namespace std;
const long long N = 1e6 + 5;
const long long mod = 998244353;
const long long INF = 0x7f7f7f7f7f7f7f7f;
const int INFi = 0x7f7f7f7f;
long long test = 1, n;
vector<pair<long long, long long> > v;
map<pair<long long, long long>, long long> ct;
void solve() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    int x, y;
    cin >> x >> y;
    v.push_back({x, y});
  }
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      int mx = v[i].first + v[j].first, my = v[i].second + v[j].second;
      ct[{mx, my}]++;
    }
  }
  long long ans = 0;
  for (auto it : ct) {
    ans += (it.second - 1) * it.second / 2;
    ans %= mod;
  }
  cout << ans << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << fixed;
  cout << setprecision(15);
  ;
  for (int i = 1; i <= test; i++) {
    solve();
  }
}
