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 read() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
struct node {
  int x, id;
} re[205000];
int s[205000], a[205000], mx[205000 * 2];
int n, d, cnt;
void build(int i, int l, int r) {
  if (l == r) {
    mx[i] = s[l];
    return;
  }
  int mid = (l + r) / 2;
  build(i * 2, l, mid);
  build(i * 2 + 1, mid + 1, r);
  mx[i] = max(mx[i * 2], mx[i * 2 + 1]);
}
int ask(int i, int l, int r, int x, int y) {
  if (x <= l && r <= y) return mx[i];
  int mid = (l + r) / 2;
  int ans = 0;
  if (x <= mid) ans = max(ans, ask(i * 2, l, mid, x, y));
  if (y > mid) ans = max(ans, ask(i * 2 + 1, mid + 1, r, x, y));
  return ans;
}
int main() {
  n = read();
  d = read();
  int gg = 0;
  for (int i = 1; i <= n; i++) {
    a[i] = read();
    s[i] = s[i - 1] + a[i];
    if (a[i] == 0) {
      if (s[i] < 0) re[++cnt] = (node){s[i], i}, s[i] = 0;
    }
    if (s[i] > d) gg = 1;
  }
  if (gg) {
    puts("-1");
    return 0;
  }
  build(1, 1, n);
  int ans = cnt;
  for (int i = 2; i <= cnt; i++) {
    while (1) {
      int l = re[i - 1].id, r = re[i].id - 1;
      if (ask(1, 1, n, l, r) - re[i].x > d) break;
      ans--;
      i++;
      if (i == cnt + 1) break;
    }
  }
  printf("%d\n", ans);
}
