#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); i ++)
using namespace std;

int main()
{
  int N; scanf("%d", &N);
  int A[N];
  rep(i,N) cin >> A[i];
  sort(A, A + N);
  int sum = A[0];
  
  for (int i = 1; i < N; i ++)
  {
    if (A[i] > A[i - 1] + 1) sum += A[i];
  }
  cout << sum << "\n";
  
  return 0;
}