/*
 * author: pavveu
 * task: Potyczki Algorytmiczne 2020 Runda 2 - Elektrownie i fabryki [B] 
*/

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

#define FOR(iter, val) for(int iter = 0; iter < (val); iter++)
#define all(x) begin(x), end(x)

vi generate_array(int n, int bound) {
	vector<int> a;
	for (int i = 0; i < n; i++) {
		int l = rand() % (2 * bound + 1) - bound;
		a.push_back(l);
	}
	return a;
}

int brute(const vi& a) {
	int n = a.size();
	int ans { n };
	int best_mask = -1;
	for (int mask = 0; mask < (1<<(n - 1)); mask++) {
		bool valid = true;

		ll prefix_sum { a[0] };
		for (int i = 0; i < n - 1; i++) {
			if ( !(mask & (1<<i)) ) {
				if ( prefix_sum < 0 ) valid = false;
				prefix_sum = 0;
			}
			prefix_sum += a[i + 1];
		}
		if ( prefix_sum < 0 ) 
			valid = false;

		if ( valid ) {
			int cost { __builtin_popcount(mask) };

			if ( ans > cost ) {
				ans = cost;
				best_mask = mask;
			}
		}
	}

	for (int i = 0; i < n - 1; i++) {
		if ( best_mask & (1<<i) ) 
			cout << "-";
		else 
			cout << ".";
	}
	cout << endl;

	return (ans == n ? -1 : ans);
}

int solution(const vi& a) {
	ll queue_sum { accumulate(all(a), 0ll) };
	if ( queue_sum < 0ll ) {
		return -1;
	}

	// next number in a pipe of a
	queue<int> q;
	// sum for every created segment
	stack<int> s;

	for (int x : a) q.push(x);

	// inf > a[i]
	const int inf = 1e9 + 1000;

	// wardens
	q.push(-inf);
	s.push(-inf);

	ll stack_sum { 0 };

	int cost { 0 };
	while ( q.size() > 1 ) {
		ll current { q.front() };
		queue_sum -= q.front();
		q.pop();


		while ( current < 0 ) {
			cost++;

			if ( stack_sum + current >= 0 && queue_sum + current >= 0 ) {
				if ( s.top() > q.front() ) {
					// cerr << "stack wins with: " << s.top() << endl;
					current += s.top();
					stack_sum -= s.top();
					s.pop();
				}
				else {
					// cerr << "queue wins with: " << q.front() << endl;
					current += q.front();
					queue_sum -= q.front();
					q.pop();
				}
			}
			else {
				if ( stack_sum + current >= 0 ) {
					// cerr << "only stack valid" << endl;
					current += s.top();
					stack_sum -= s.top();
					s.pop();
				}
				else if ( queue_sum + current >= 0 ) {
					// cerr << "only queue valid" << endl;
					current += q.front();
					queue_sum -= q.front();;
					q.pop();
				}
				else {
					assert("No solution?");
				}
			}
		}

		s.push(current);
		stack_sum += current;
		// cerr << "stack sum: " << stack_sum << endl;
	}

	// stack contains warden, so size - 1
	int segments_left = s.size() - 1;
	int max_links = a.size() - 1;
	int links_left { segments_left - 1 };

	return max_links - links_left;
}

void test(int times = 1) {
	srand(time(NULL));

	FOR(t, times) {
		vi a { generate_array(10, 10) };
		int sol { solution(a) };
		int br { brute(a) };

		reverse(all(a));
		int sol2 { solution(a) };

		reverse(all(a));

		if ( sol != br || sol2 != br ) {
			cout << "ERROR" << endl;
			cout << "SOL: " << sol << endl;
			cout << "SOL2: " << sol2 << endl;
			cout << "BRUTE: " << br << endl;
			cout <<"A: ";

			for (int x : a ) {
				cout << x << " ";
			}
			cout << endl;
			break;
		}
		else {
			cout << "OK.\n";
		}
	}
}

void go() {
	int n; cin >> n;
	vi a(n);
	for (auto& i : a) cin >> i;

	int sol1 { solution(a) };
	reverse(all(a));
	int sol2 { solution(a) };
	cout << std::min(sol1, sol2) << endl;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	go();
	// test(100);

	return 0;
}