//@Author: KeinYukiyoshi

// clang-format off
#include <bits/stdc++.h>
//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx")
#define int long long
using namespace std;
#define stoi stoll
#define fi first
#define se second
#define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; i++)
#define rep2(i, a, b) for (int i = (int)(a), i##_len=(b); i < i##_len; i++)
#define rep3(i, a, b) for (int i = (int)(a), i##_len=(b); i >= i##_len; i--)
#define FOR(i, a) for (auto &i: a)
#define ALL(obj) begin(obj), end(obj)
#define _max(x) *max_element(ALL(x))
#define _min(x) *min_element(ALL(x))
#define _sum(x) accumulate(ALL(x), 0LL)

const int MOD   = 1000000007;
// const int MOD    = 998244353;
// const int INF    = (int)1e18;
// const int INF    = 10000000000007; // 1e13 + 7
// const int INF    = LLONG_MAX; // 9.2e18
const double EPS = 1e-8;
const double PI  = 3.14159265358979;
template <class T> using V = vector<T>;
template <class T> using VV = vector<vector<T>>;
template <class T> using VVV = vector<vector<vector<T>>>;
template <class T, class S>  using P = pair<T, S>;
template<class T> bool chmax(T &a, const T &b) {if (a < b) {a = b;return true;}return false;}
template<class T> bool chmin(T &a, const T &b) {if (b < a) {a = b;return true;}return false;}
int _ceil(int a, int b) { return (a >= 0 ? (a + (b - 1)) / b : (a - (b - 1)) / b); }
template<class T> T chmod(T &a, T mod=MOD) {a =  a >= 0 ? a % mod : a - (mod * _ceil(a, mod)); return a;};
int _mod(int a, int mod=MOD) {return a >= 0 ? a % mod : a - (mod * _ceil(a, mod));}
int _pow(int a, int b) {int res = 1;for (a %= MOD; b; a = a * a % MOD, b >>= 1)if (b & 1) res = res * a % MOD;return res;}
struct mint {long long x;mint(long long x = 0) : x((x % MOD + MOD) % MOD) {}mint operator-() const { return mint(-x); }mint &operator+=(const mint a) {if ((x += a.x) >= MOD) x -= MOD;return *this;}mint &operator-=(const mint a) {if ((x += MOD - a.x) >= MOD) x -= MOD;return *this;}mint &operator*=(const mint a) { (x *= a.x) %= MOD;return *this; }mint operator+(const mint a) const { return mint(*this) += a; }mint operator-(const mint a) const { return mint(*this) -= a; } mint operator*(const mint a) const { return mint(*this) *= a; }mint pow(long long t) const {if (!t) return 1;mint a = pow(t >> 1);a *= a;if (t & 1) a *= *this;return a;}mint inv() const { return pow(MOD - 2); }mint &operator/=(const mint a) { return *this *= a.inv(); }mint operator/(const mint a) const { return mint(*this) /= a; }};istream &operator>>(istream &is, mint &a) { return is >> a.x; }ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }
// clang-format on

class CRingosFavoriteNumbers2 {
public:
  static void solve(istream &cin, ostream &cout) {
    cin.tie(nullptr);
    cout.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
    int N;
    cin >> N;
    V<int> A(N);
    rep(i, N) cin >> A[i];
    rep(i, N) A[i] = A[i] % 200;
    V<int> check(200);
    rep(i, N) check[A[i]]++;
    int ans = 0;
    rep(i, 200) ans += check[i] * (check[i] - 1) / 2;
    cout << ans << endl;
  }
};


signed main() {
  CRingosFavoriteNumbers2 solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  solver.solve(in, out);
  return 0;
}


#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pi;
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define rep(i,a,b) for (int i = a; i < b; i++)
const int INF =2e5+1;
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
    int t=1 ; 
    ll f[INF];
    f[1]=1;
    for(int i =2;i<INF;i++){
        f[i]=f[i-1]+i;
    }
   while(t--){
       int n ; 
       cin>>n ; 
       int a[n];
       for(int i =0;i<n;i++){
           cin>>a[i];
           a[i]%=200;
       }
       sort(a,a+n);
       ll ans = 0;
       int num = 0 ; 
       for(int i = 1 ; i<n;i++){
           if(a[i]==a[i-1]){
               num++;
           }
           else if (num>=1) {
               ans += f[num];
               num=0;
           }
           else {num = 0;}
       }
       if (num>=1) {
               ans += f[num];
           }
           else {num = 0;}
     
cout<<ans<<endl;

   }
}