//**He who has a why can survive almost any how***
 
#include<bits/stdc++.h>
using namespace std;
 
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define ll long long 
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define rep(i,n) for(i=0;i<n;i++)
#define forn(i, n) for (ll i = 0; i < (ll)(n); ++i)
#define for1(i, n) for (ll i = 1; i <= (ll)(n); ++i)
#define ford(i, n) for (ll i = (ll)(n) - 1; i >= 0; --i)
#define fore(i, a, b) for (ll i = (ll)(a); i <= (ll)(b); ++i)
#define fora(it,x) for(auto it:x)
#define PI 3.14159265
#define sync ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define endl "\n"
 
typedef pair<ll, ll> pii;
typedef vector<ll> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef long long i64;
typedef vector<i64> vi64;
typedef vector<vi64> vvi64;
typedef pair<i64, i64> pi64;
typedef long double ld;
 
template<class T> bool uin(T &a, T b) { return a > b ? (a = b, true) : false; }
template<class T> bool uax(T &a, T b) { return a < b ? (a = b, true) : false; }

int main(){
	ll n,ans=0;
	cin>>n;
	ll a[n+5],fr[200]={0};
	forn(i,n) cin>>a[i];

	forn(i,n){
		ll cur=a[i]%200;
		ans+=fr[cur];
		fr[cur]++;
	}
	cout<<ans;
}
#include <bits/stdc++.h>

using namespace std;

#define all(x) (x).begin(), (x).end()

typedef long long ll;

void solve() {
  int n; cin >> n;
  vector<int> cnt(200);
  ll ans = 0;
  for (int i = 0; i < n; i++) {
    int v; cin >> v;
    ans += cnt[v % 200];
    cnt[v % 200]++;
  }
  cout << ans << "\n";
}

int main() {
  ios::sync_with_stdio(NULL), cin.tie(0), cout.tie(0);
  cout.setf(ios::fixed), cout.precision(20);
  //cout << 1.0 * clock() / CLOCKS_PER_SEC << endl;
  solve();
}
