#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  vector<long long> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
  }
  sort(A.rbegin(), A.rend());
  set<long long> st;
  for (int i = 0; i < N; i++){
    st.insert(A[i]);
  }
  vector<vector<vector<long long>>> P(2);
  for (int i = 0; i < N; i++){
    int r = A[i] % 2;
    if (st.count(A[i] + 2)){
      P[r].back().push_back(A[i]);
    } else {
      P[r].push_back(vector<long long>(1, A[i]));
    }
  }
  long long ans = N;
  for (int i = 0; i < 2; i++){
    int cnt = P[i].size();
    for (int j = 0; j < cnt; j++){
      int sz = P[i][j].size();
      for (int k = 0; k < sz; k++){
        if (st.count(P[i][j][k] - 1)){
          ans += k + 1;
        }
      }
    }
  }
  cout << ans << endl;
}