9 13
6 14 19 5 -5 6 -10 20 8
 8 9
6 -1 5 -5 -8 -7 -8 -7
 10 7
-9 3 -4 -22 4 -17 0 -14 3 -2
 6 2
-2 3 0 -2 0 0
 5 10
-8 -24 0 -22 12
 5 13756
-2 -9 -10 0 10
 7 3
1 -3 0 3 -1 0 2
 9 9
-3 2 0 -2 -7 -1 0 5 3
 2 3
2 0
 19 78701
1 0 -1 0 -1 -1 0 1 0 -1 1 1 -1 1 0 0 -1 0 0
 5 4
-1 0 0 1 -1
 6 4
-1 0 2 -4 0 5
 20 23036
-1 1 -1 -1 -1 -1 1 -1 -1 0 0 1 1 0 0 1 0 0 -1 -1
 5 4
-1 0 -3 0 3
 12 82016
1 -2 -1 -1 -2 -1 0 -2 -1 1 -2 2
 7 4
-6 0 2 -3 0 4 0
 4 4
2 2 0 1
 6 1
-3 0 0 0 -2 3
 8 26
-4 9 -14 -11 0 7 23 -15
 20 23079
0 1 1 -1 1 0 -1 -1 0 0 1 -1 1 1 1 0 0 1 0 1
 1 1
1
 7 8555
-2 -3 -2 3 0 -2 0
 4 100
-100 0 -50 100
 3 14
12 12 -8
 1 1
2
 10 23
9 7 14 16 -13 -22 24 -3 -12 14
 8 11
12 -12 -9 3 -22 -21 1 3
 19 49926
-2 0 2 0 0 -2 2 -1 -1 0 0 0 1 0 1 1 -2 2 2
 16 76798
-1 11 -7 -4 0 -11 -12 3 0 -7 6 -4 8 6 5 -10
 9 5
-2 0 3 -4 0 4 -3 -2 0

-1
 -1
 1
 1
 1
 1
 -1
 2
 0
 1
 1
 -1
 1
 1
 1
 1
 -1
 1
 -1
 0
 0
 1
 1
 -1
 -1
 -1
 -1
 1
 1
 1

#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e9 + 123, MAXN = 2e5 + 47;
template <class T>
istream& operator>>(istream& in, vector<T>& a) {
  for (auto& i : a) in >> i;
  return in;
}
template <class T>
ostream& operator<<(ostream& out, vector<T>& a) {
  for (auto& i : a) out << i << " ";
  return out;
}
template <class T, class D>
istream& operator>>(istream& in, vector<pair<T, D>>& a) {
  for (auto& i : a) in >> i.first >> i.second;
  return in;
}
template <class T, class D>
ostream& operator<<(ostream& out, vector<pair<T, D>>& a) {
  for (auto& i : a) out << i.first << " " << i.second << endl;
  return out;
}
signed main() {
  setlocale(LC_ALL, "rus");
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, d;
  cin >> n >> d;
  vector<long long> a(n);
  cin >> a;
  vector<long long> pref(n);
  pref[0] = a[0];
  long long ans = 0;
  vector<long long> suff(n);
  suff.back() = a.back();
  for (long long i = n - 2; i >= 0; --i)
    suff[i] = max({suff[i + 1] + a[i], suff[i], 0ll, a[i]});
  if (pref[0] > d) return cout << -1, 0;
  for (long long i = 1; i < n; ++i) {
    pref[i] = pref[i - 1] + a[i];
    if (a[i] == 0) {
      if (pref[i] < 0) {
        ++ans;
        pref[i] = d - suff[i];
        if (pref[i] < 0) return cout << -1, 0;
      }
    }
    if (pref[i] > d) return cout << -1, 0;
  }
  cout << ans;
}
