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>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse4")
using namespace std;
long long n, d;
long long a[100005], pre[100005];
vector<long long> v, m, ind;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> d;
  long long i;
  for (i = 1; i <= n; i++) cin >> a[i];
  long long maxi = -1e18;
  for (i = 1; i <= n; i++)
    if (a[i] == 0) {
      if (pre[i - 1] < 0) {
        m.push_back(maxi);
        if (maxi > d) {
          cout << -1;
          return 0;
        }
        ind.push_back(i);
        v.push_back(abs(pre[i - 1]));
        maxi = -1e18;
        pre[i] = 0;
      } else
        pre[i] = pre[i - 1];
    } else {
      pre[i] = pre[i - 1] + a[i];
      maxi = max(maxi, pre[i]);
    }
  if (maxi > d) {
    cout << -1;
    return 0;
  }
  if (v.size() == 0) {
    cout << 0;
    return 0;
  }
  if (v.size() == 1) {
    cout << 1;
    return 0;
  }
  long long ans = 1;
  maxi = d - m[1];
  long long sum = 0;
  for (i = 1; i < v.size(); i++) {
    if (v[i] > maxi) {
      ans++;
      if (sum + m[i] <= d) {
        sum = 0;
        if (i + 1 < v.size()) maxi = d - m[i + 1];
      } else {
        sum = 0;
        maxi = d - m[i];
        i--;
      }
    } else {
      maxi -= v[i];
      sum += v[i];
      if (i + 1 < v.size()) {
        if (d - m[i + 1] < maxi) maxi = d - m[i + 1];
      }
    }
  }
  cout << ans;
  return 0;
}
