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#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <deque>
#include <climits>
using namespace std;
void input (int &n, vector<long long> &arr) {
  int x;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x;
    arr.push_back(x);
  }
}
int solve(int &n, vector<long long> &arr) {
  vector<int> dp(n + 1, -1);
  dp[0] = 0;
  for (int i = 0; i < n; i++) {
    if (dp[i] < 0) continue;
    long long sum = 0;
    for (int j = i; j < n; j++) {
      sum += arr[j];
      if (sum >= 0) dp[j + 1] = max(dp[j + 1], dp[i] + 1);
    }
  }
  if (dp[n] == -1) return -1;
  else return n - dp[n];
}
int main() {
  ios_base::sync_with_stdio(0);
  int n;
  vector<long long> arr;
  input(n, arr);
  cout << solve(n, arr) << "\n";
  return 0;
}