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 mod = 1e9 + 7;
const int N = 1e5 + 10;
int a[N];
int n, d;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> d;
  long long m = 0;
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
    if (!a[i]) {
      m++;
    }
  }
  m++;
  long long maxbal[m];
  vector<long long> sum[m];
  long long acc[m];
  long long i = 0;
  long long j = 0;
  while (i != m) {
    while (a[j] != 0) {
      sum[i].push_back(a[j]);
      j++;
    }
    j++;
    acc[i] = 0;
    if (!sum[i].empty()) {
      acc[i] = accumulate(sum[i].begin(), sum[i].end(), 0);
      if (acc[i] > d) {
        cout << -1;
        return 0;
      }
    }
    i++;
  }
  for (long long i = 0; i < m; i++) {
    for (long long j = 1; j < sum[i].size(); j++) {
      sum[i][j] += sum[i][j - 1];
    }
    sort(sum[i].begin(), sum[i].end());
    if (sum[i].empty() == false && sum[i].back() > d) {
      cout << -1;
      return 0;
    }
  }
  for (long long i = m - 2; i >= 0; i--) {
    maxbal[i] = 0;
    if (acc[i + 1] > d && i == m - 2) {
      cout << -1;
      return 0;
    }
    if (i == m - 2) {
      if (acc[i + 1] <= d && acc[i + 1] >= 0) {
        maxbal[i] = d - acc[i + 1];
      } else if (acc[i + 1] < 0) {
        maxbal[i] = d;
      }
      continue;
    }
    if (!sum[i + 1].empty() && sum[i + 1].back() <= d &&
        sum[i + 1].back() >= 0) {
      maxbal[i] = maxbal[i + 1] - sum[i + 1].back();
    } else if (!sum[i + 1].empty() && sum[i + 1].back() < 0) {
      if (maxbal[i + 1] - sum[i + 1].back() < d) {
        maxbal[i] = maxbal[i + 1] - sum[i + 1].back();
      } else {
        cout << -1;
        return 0;
        maxbal[i] = d;
      }
    } else {
      maxbal[i] = maxbal[i + 1];
    }
    if (maxbal[i] > d) {
      cout << -1;
      return 0;
    }
  }
  long long bal = 0;
  long long cnt = 0;
  long long k = 0;
  for (long long i = 0; i < n; i++) {
    if (a[i] != 0) {
      bal += a[i];
    } else {
      if (bal < 0) {
        bal = maxbal[k];
        cnt++;
      }
      k++;
    }
    if (bal > d) {
      cout << -1;
      return 0;
    }
  }
  cout << cnt;
  return 0;
}
