#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VI a(n);
  rep(i, n) cin >> a[i];
  ll ans = accumulate(all(a) - 1, 0LL) + a[0];
  vector<char> exists(1000001);
  for (int x : a) exists[x] = true;
  constexpr int INF = 1001001001;
  VI dp(1000001, INF);
  struct S {
    int cost, upto, add;
  };
  auto cmp = [](const S& x, const S& y) {
    return x.cost > y.cost;
  };
  priority_queue<S, vector<S>, decltype(cmp)> q(cmp);
  for (int i = a[0]; i <= a[n - 1]; i++) {
    if (!exists[i]) continue;
    int c = [&] {
      if (i == a[0]) return 0;
      while(q.top().upto <= i) {
        auto [cost, upto, add] = q.top(); q.pop();
        q.push({cost + add, upto + add, add});
      }
      return q.top().cost - i;
    }();
    if (i == a[n - 1]) {
      ans -= c;
      break;
    }
    q.push({c + i + i, i + i, i});
  }
  cout << ans << '\n';
}