#include <bits/stdc++.h>
using namespace std;
int main() {

   int N;
   cin >> N;
   vector<long long> L(N);
   for (int i = 0; i < N; i++) {
       cin >> L[i];
   }
   sort(L.begin(), L.end());
   long long opened = 0;
   int remaining = N;
   for (int i = 0; i < N && remaining > 1; i++) {
       if (opened >= remaining - 1) break;
       long long need = remaining - 1 - opened;
       long long take = min(L[i], need);
       opened += take;
       if (take == L[i]) remaining--;
   }
   cout << opened << "\n";
   return 0;
}