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 long long INF = 1e17;
const int MOD = 1e9 + 7;
const int N = 1e5;
struct Tree {
  long long maxi, lazy;
  Tree() { lazy = 0; }
};
int n, d;
long long a[N], b[N];
Tree tree[N * 4];
void build(int id, int l, int r) {
  if (l == r) {
    tree[id].maxi = b[l];
    return;
  }
  int m = (l + r) / 2;
  build(id << 1, l, m);
  build((id << 1) + 1, m + 1, r);
  tree[id].maxi = max(tree[id << 1].maxi, tree[(id << 1) + 1].maxi);
}
void update(int id, int l, int r, int i, int j, long long k) {
  if (tree[id].lazy != 0) {
    tree[id].maxi += tree[id].lazy;
    if (l != r) {
      tree[id << 1].lazy += tree[id].lazy;
      tree[(id << 1) + 1].lazy += tree[id].lazy;
    }
    tree[id].lazy = 0;
  }
  if (l > j || r < i) return;
  if (l >= i && r <= j) {
    tree[id].maxi += k;
    if (l != r) {
      tree[id << 1].lazy += k;
      tree[(id << 1) + 1].lazy += k;
    }
    return;
  }
  int m = (l + r) / 2;
  update(id << 1, l, m, i, j, k);
  update((id << 1) + 1, m + 1, r, i, j, k);
  tree[id].maxi = max(tree[id << 1].maxi, tree[(id << 1) + 1].maxi);
}
long long query(int id, int l, int r, int i, int j) {
  if (l > j || r < i) return -INF;
  if (l >= i && r <= j) return tree[id].maxi;
  int m = (l + r) / 2;
  long long ql = query(id << 1, l, m, i, j);
  long long qr = query((id << 1) + 1, m + 1, r, i, j);
  return max(ql, qr);
}
void init() {}
int main() {
  init();
  scanf("%d %d", &n, &d);
  for (int i = 0; i < n; i++) scanf("%lld", &a[i]);
  b[0] = a[0];
  for (int i = 1; i < n; i++) b[i] = b[i - 1] + a[i];
  build(1, 0, n - 1);
  int ans = 0;
  long long cur = 0;
  for (int i = 0; i < n; i++) {
    cur = cur + a[i];
    if (cur > d) return 0 * puts("-1");
    if (a[i] == 0 && cur < 0) {
      long long maxi = query(1, 0, n - 1, i, n - 1);
      long long add = d - maxi;
      if (d - maxi < -cur) return 0 * puts("-1");
      update(1, 0, n - 1, i, n - 1, add);
      cur += add;
      ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
