#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1000000007;
using P = pair<int,int>;
#define rep(i, n) for(int i = 0; i < n; i++)
#define all(x) (x).begin(),(x).end()

int main(){
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i,n) cin >> a[i];
    sort(all(a));
    ll ans = a[0];
    rep(i,n-1) if(a[i+1]-1 != a[i]) ans += a[i+1];
    cout << ans << endl;
    return 0;
}