1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
#include <stdio.h>
#include <climits>
#include <algorithm>
#include <cstdlib>
#include <map>

using namespace std;

int n;
long long int sum = 0ll;
long long int a;
long long int in[501*1000];
map<long long int, long long int> lowest;
map<long long int, long long int>::iterator it;
long long int cur = 0ll, len = 0ll;


void add(long long int npc, long long int npl) {
  long long int lowest_val = npl;
  it = lowest.find(npc);
  if(it != lowest.end()) {
    lowest_val = min(npl, it->second);
    lowest.erase(it);
  }
  lowest.insert({npc, lowest_val});
  while(true) {
    it = lowest.find(npc);
    if(it != lowest.begin()) {
      --it;
      if(it->second >= lowest_val) {
        lowest.erase(it);
      } else {
        break;
      }
    } else {
      break;
    }
  }
}

long long int find_lowest_legal_l() {
  long long int ret = LLONG_MAX;
  it = lowest.lower_bound(0ll - cur);
  if(it != lowest.end()) {
    ret = it->second;
  }
  return ret;
}


int main() {
  scanf("%lld", &n);
  for(int i = 0; i < n; i++) {
    scanf("%lld", &a);
    sum += a;
    in[i] = a;
  }
  if(sum < 0ll) {
    printf("-1");
    return 0;
  }

  add(in[0], 0ll);
  for(int i = 1; i < n; i++) {
    long long int l = find_lowest_legal_l();
    if(l != LLONG_MAX) {  // Yes, we can try to omit
      add(0ll-cur, l-1);
    }
    cur += in[i];
    len++;
  }

  printf("%lld", find_lowest_legal_l() + len);
  return 0;
}