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