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

void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int main() {
    fast_io();
    int n;
    cin >> n;
    vector<int> a(n);
    for (int &i : a) {
        cin >> i;
    }
    sort(a.begin(), a.end());
    int ans = a[0];
    for (int i = 1; i < n; i++) {
        if (a[i] != a[i - 1] + 1) {
            ans += a[i];
        }
    }
    cout << ans << endl;
}