#include<bits/stdc++.h>
//#include<atcoder/all>

using namespace std;
//using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using P = pair<int,int>;
#define rep(i,n) for(ll i = 0;i < (ll)n;i++)
#define ALL(x) (x).begin(),(x).end()
#define MOD 1000000007

vector<ll> dp(200100,-1);
ll dfs(vector<ll> &v,int pos){
  if(pos >= v.size())return 0;
  ll res = 0;
  for(int i = 1;i <= 2;i++){
    if(pos+i >= v.size())break;
    if(v[pos+i]-v[pos] == 2)res += dfs(v,pos+i);
  }
  return dp[pos] = res+1;
}

int main(){
  
  int n;
  cin >> n;
  vector<ll> v(n);
  rep(i,n)cin >> v[i];
  sort(ALL(v));
  vector<int> l(n);
  rep(i,n)dfs(v,i);
  ll res = n;
  for(int i = 1;i < n;i++)if(v[i]-v[i-1] == 1)res += dp[i];
  cout << res << "\n";


  return 0;
}