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 double PI = acos(-1.0);
const int N = 1e5 + 7;
long long arr[N], pre[N];
struct seg {
  int l, mid, r;
  long long v, mx, ad;
} T[N << 2];
void pushup(int k) { T[k].mx = max(T[(k << 1)].mx, T[((k << 1) + 1)].mx); }
void pushdown(int k) {
  if (T[k].ad) {
    T[(k << 1)].ad += T[k].ad;
    T[((k << 1) + 1)].ad += T[k].ad;
    T[(k << 1)].v += T[k].ad;
    T[((k << 1) + 1)].v += T[k].ad;
    T[k].ad = 0;
  }
}
void build(int k, int l, int r) {
  T[k].l = l;
  T[k].r = r;
  T[k].mid = ((l + r) >> 1);
  T[k].ad = 0;
  if (l == r)
    T[k].mx = T[k].v = pre[l];
  else {
    build((k << 1), l, T[k].mid);
    build(((k << 1) + 1), T[k].mid + 1, r);
    pushup(k);
  }
}
void update(int k, int l, int r, long long v) {
  if (l <= T[k].l && T[k].r <= r) {
    T[k].ad += v;
    T[k].mx += v;
    T[k].v += v;
  } else {
    pushdown(k);
    if (l <= T[k].mid) update((k << 1), l, r, v);
    if (r > T[k].mid) update(((k << 1) + 1), l, r, v);
    pushup(k);
  }
}
long long query(int k, int l, int r) {
  if (l <= T[k].l && T[k].r <= r)
    return T[k].mx;
  else {
    pushdown(k);
    if (r <= T[k].mid)
      return query((k << 1), l, r);
    else if (l > T[k].mid)
      return query(((k << 1) + 1), l, r);
    else
      return max(query((k << 1), l, T[k].mid),
                 query(((k << 1) + 1), T[k].mid + 1, r));
  }
}
int main(void) {
  int n, i;
  long long d;
  scanf("%d%I64d", &n, &d);
  for (i = 1; i <= n; ++i) {
    scanf("%I64d", &arr[i]);
    pre[i] = pre[i - 1] + arr[i];
    if (pre[i] > d) return puts("-1");
  }
  build(1, 1, n);
  int day = 0;
  for (i = 1; i <= n; ++i) {
    if (arr[i] == 0) {
      pre[i] = query(1, i, i);
      if (pre[i] < 0) {
        long long sufmax = query(1, i, n);
        long long delta = d - sufmax;
        update(1, i, n, delta);
        if (pre[i] + delta < 0)
          return puts("-1");
        else
          ++day;
      }
    }
  }
  printf("%d\n", day);
  return 0;
}
