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 N, D, a[100100], bbh[100100], tree[300100];
const long long inf = 2e15;
void update(long long n, long long s, long long e, long long si, long long ei,
            long long v) {
  if (s > ei || e < si) return;
  if (s >= si && e <= ei) {
    tree[n] = v;
    return;
  }
  long long lch = 2 * n, rch = 2 * n + 1, m = s + e >> 1;
  update(lch, s, m, si, ei, v);
  update(rch, m + 1, e, si, ei, v);
  tree[n] = max(tree[lch], tree[rch]);
}
long long query(long long n, long long s, long long e, long long si,
                long long ei) {
  if (s > ei || e < si) return -inf;
  if (s >= si && e <= ei) return tree[n];
  long long m = s + e >> 1;
  return max(query(2 * n, s, m, si, ei), query(2 * n + 1, m + 1, e, si, ei));
}
int main() {
  long long i, j, now = 0, max1 = -1, up = 0, cnt = 0;
  cin >> N >> D;
  for (i = 1; i <= N; i++)
    cin >> a[i], bbh[i] = bbh[i - 1] + a[i], update(1, 1, N, i, i, bbh[i]);
  for (i = 1; i <= N; i++) {
    if (a[i] == 0) now = min(bbh[i], now);
    max1 = max(max1, bbh[i] - now);
  }
  if (max1 > D) {
    cout << -1;
    return 0;
  }
  for (i = 1; i <= N; i++) {
    if (a[i] == 0 && bbh[i] < -up) {
      up += (D - query(1, 1, N, i + 1, N));
      cnt++;
    }
  }
  cout << cnt;
}
