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 int inf = (int)1e9;
const int mod = inf + 7;
const double eps = 1e-9;
const double pi = acos(-1.0);
int n, d;
int a[100100];
long long pr[100100], mx[100100];
long long L[100100], R[100100];
bool can(int ind, long long val) {
  if (ind == n) return true;
  if (val > R[ind]) return false;
  return can(ind + 1, max(val, L[ind]));
}
int main() {
  scanf("%d%d", &n, &d);
  for (int i = 0; i < n; i++) {
    scanf("%d", a + i);
    pr[i] = a[i];
    if (i) pr[i] += pr[i - 1];
  }
  int cur = 0;
  bool ok = true;
  for (int i = 0; i < n; i++) {
    cur += a[i];
    if (cur > d || (a[i] == 0 && cur < 0)) ok = false;
  }
  if (ok) {
    printf("0\n");
    return 0;
  }
  mx[n - 1] = pr[n - 1];
  for (int i = n - 2; i >= 0; i--) {
    mx[i] = max(mx[i + 1], pr[i]);
  }
  for (int i = 0; i < n; i++) {
    L[i] = 0;
    R[i] = d - pr[i];
    if (a[i] == 0) L[i] = max(L[i], -pr[i]);
    if (L[i] > R[i]) {
      printf("-1\n");
      return 0;
    }
  }
  if (!can(0, L[0])) {
    printf("-1\n");
    return 0;
  }
  long long l = L[0];
  long long r = R[0];
  int ans = 0;
  for (int i = 0; i < n; i++) {
    if (l > R[i] || r < L[i]) {
      if (l <= 0 && r >= 0)
        ;
      else
        ans++;
      l = L[i];
      r = R[i];
    } else {
      l = max(l, L[i]);
      r = min(r, R[i]);
    }
  }
  if (l <= 0 && r >= 0)
    ;
  else
    ans++;
  printf("%d\n", ans);
  return 0;
}
