#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    int n, temp;
    cin >> n;
    vector<int> v;
    for (int i = 0; i < n; i++){
        cin >> temp;
        v.push_back(temp);
    }
    sort(v.begin(), v.end());
    int sum1 = v[0];
    for (int i = 0; i < n-1; i++) if (v[i] != (v[i+1] - 1)) sum1 += v[i+1];
    
    cout << sum1 << endl;
}