#include <bits/stdc++.h>
using namespace std;
using G=vector<vector<int>>;
typedef long long ll;
#define rep(i,l,r) for(int i=(l);i<(r);++i)

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