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#if defined(EMBE_DEBUG) && !defined(NDEBUG)
#include "embe-debug.hpp"
#else
#define LOG_INDENT(...) do {} while (false)
#define LOG(...) do {} while (false)
#define DUMP(...) do {} while (false)
#endif

#include <iostream>
#include <map>
#include <optional>
#include <vector>
using namespace std;

namespace {

class State {
private:
  map<long long, int> current;

  long long energy_bias = 0;
  int cost_bias = 0;

public:
  void insert(long long e, int c)
  {
    e -= energy_bias;
    c -= cost_bias;
    auto it = current.lower_bound(e);
    if (it != current.end() && it->second <= c) return;
    it = current.insert_or_assign(it, e, c);
    while (it != current.begin()) {
      auto it2 = prev(it);
      if (it2->second < c) break;
      current.erase(it2);
    }
  }

  void add_energy(long long e)
  {
    energy_bias += e;
  }

  void add_cost(int c)
  {
    cost_bias += c;
  }

  optional<int> find(long long e)
  {
    e -= energy_bias;
    auto it = current.lower_bound(e);
    if (it == current.end()) return {};
    return it->second + cost_bias;
  }
};

int solve(vector<int> const& cities)
{
  State state;
  state.insert(0, 0);
  for (auto const& c: cities) {
    state.add_energy(c);
    auto ending = state.find(0);
    state.add_cost(1);
    if (ending) {
      state.insert(0, *ending);
    }
  }
  return state.find(0).value_or(-1);
}

}

int main()
{
  iostream::sync_with_stdio(false);
  cin.tie(nullptr);

  int n;
  cin >> n;
  vector<int> cities(n);
  for (auto& c: cities) {
    cin >> c;
  }

  cout << solve(cities) << '\n';

  return 0;
}