#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(LL i = a;i<b; i++)
#define rrep(i,a,b) for(LL i = a;i>b; i--)
#define INF ((1LL<<62)-(1LL<<31))
#define ooki 9,223,372,036,854,775,807
#define tii -9,223,372,036,854,775,808
typedef long long LL;
int main(){
  int n,sum=0;
  cin>>n;
  vector<int> a(n);
  rep(i,0,n){cin>>a[i];}
  sort(a.begin(),a.end());
   rep(i,1,n){
     if(a[i]-a[i-1]!=1){sum+=a[i];}
   }
  cout<<sum+a[0]<<endl;
     
     
}