#include <iostream>
#include <algorithm>
using namespace std;
int arr[100001];
int main(int argc, char *argv[])
{
int n;
long long res = 0;
cin >> n;
for (int i = 0; i < n;i++)
{
cin >> arr[i];
}
sort(arr, arr + n);
int idx = 0;
for (int i = n - 1; i >= 0;i--)
{
int a = (arr[idx] - i > 0) ? arr[idx] - i : 0;
idx++;
res += a;
}
cout << res;
}