#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>


typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;



int main()
{

    int Q;
    Q = 1;
    //cin >> Q;
    
    
    
    while (Q--) {

        int n;
        cin >> n;
        vector<int>x(n);
        
        for (int i = 0; i < n; i++)cin >> x[i];
        sort(x.begin(), x.end());
        int r = x[0];
        for (int i = 1; i < n ; i++) {
            if (x[i]  != x[i - 1]+1) {
                r += x[i];
                
            }
            
        }
        
        cout << r << endl;

    }
    return 0; 
}