#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
int main() {
	int n;
	int ans=0;
	cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a.begin(), a.end(),greater<int>());
	for (int i = 0; i < n-1; i++) {
		if (a.at(i) - 1 != a.at(i + 1)) ans += a[i];
	}
	ans += a[n-1];
	cout << ans << endl;
	return 0;
}