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;
int minCost;
int n, d;
int a[100000];
int suffSum[100001];
int mxSuffSum[100001];
int prefSum[100001];
int mxPrefSum[100001];
int main() {
  cin >> n >> d;
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  int curSum = 0;
  prefSum[0] = a[0];
  for (int i = 1; i < n; i++) {
    prefSum[i] = prefSum[i - 1] + a[i];
  }
  for (int i = n - 1; i >= 0; i--) {
    mxPrefSum[i] = max(prefSum[i], mxPrefSum[i + 1]);
  }
  for (int i = 0; i < n; i++) {
    if (i)
      mxSuffSum[i] = mxPrefSum[i] - prefSum[i - 1];
    else
      mxSuffSum[i] = mxPrefSum[i];
  }
  int ans = 0;
  for (int i = 0; i < n; i++) {
    if (!a[i]) {
      if (curSum < 0) {
        ans++;
        curSum = d;
      }
    }
    curSum += a[i];
    if (curSum > d) {
      cout << -1;
      return 0;
    }
  }
  cout << ans;
}
