#include <bits/stdc++.h>
using namespace std;
using ll = long long;


int main() {
    ll N,A,ans;
    vector<ll> veA={};
    cin >> N;
    for (int i=0;i<N;i++){
        cin >> A;
        veA.push_back(A);
    }
    sort(veA.begin(),veA.end());
    ans = veA[0];
    for (int i=1;i<N;i++){
        if(veA[i]-1!=veA[i-1]){
            ans += veA[i];
        }
    }
    cout << ans;
}