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;
long long a[100005], n;
bool t[100005];
long long sparse1[100005][20], sparse2[100005][20];
void built() {
  for (long long i = 1; i <= n; i++) {
    sparse1[i][0] = a[i];
    sparse2[i][0] = a[i];
  }
  for (long long j = 1; j < 20; j++) {
    for (long long i = 1; i <= n - (1 << j) + 1; i++) {
      sparse1[i][j] =
          max(sparse1[i][j - 1], sparse1[i + (1 << (j - 1))][j - 1]);
      sparse2[i][j] =
          min(sparse2[i][j - 1], sparse2[i + (1 << (j - 1))][j - 1]);
    }
  }
}
long long getmax(long long l, long long r) {
  long long ans = INT_MIN;
  for (long long j = 19; j >= 0; j--) {
    if (l + (1 << j) - 1 <= r) {
      ans = max(ans, sparse1[l][j]);
      l += (1 << j);
    }
  }
  return ans;
}
long long getmin(long long l, long long r) {
  long long ans = INT_MAX;
  for (long long j = 19; j >= 0; j--) {
    if (l + (1 << j) - 1 <= r) {
      ans = min(ans, sparse2[l][j]);
      l += (1 << j);
    }
  }
  return ans;
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long d = 0, l = 1, k, no = 0;
  cin >> n >> k;
  for (long long i = 1; i <= n; i++) {
    cin >> a[i];
    t[i] = (a[i] == 0);
    a[i] += a[i - 1];
  }
  built();
  for (long long i = 1; i <= n; i++) {
    if (d + a[i] > k) return cout << -1, 0;
    if (t[i] && a[i] + d < 0) {
      if (no == 0 || -a[i] + getmax(l, i) > k)
        l = i;
      else if (-a[i] + getmax(l, i) <= k)
        no--;
      no++;
      d = -a[i];
    }
  }
  cout << no;
}
