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 int mod = 1e9 + 7;
const long long int mod2 = 1e9 + 9;
const long long int maxn = 1e6 + 50;
const int root = 1e5 + 5;
const long long inf = 1e18 + 18;
double pie4 = 3.1415926535;
long long int d, a[maxn], nxt[maxn];
void die() {
  cout << "-1" << endl;
  exit(0);
}
bool check(long long int bal, long long int st, long long int en) {
  long long int sum = bal;
  for (long long int i = st; i <= en; i++) {
    sum += a[i];
    if (sum > d) return false;
  }
  return true;
}
long long int solve(long long int st, long long int en) {
  long long int low = 0, high = d, ans = -1;
  while (low <= high) {
    long long int mid = (low + high) / 2;
    if (check(mid, st, en)) {
      ans = mid;
      low = mid + 1;
    } else
      high = mid - 1;
  }
  return ans;
}
int main() {
  long long int n, i, bal, ans = 0;
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> d;
  long long int idx = 0;
  for (i = 1; i <= n; i++) {
    cin >> a[i];
    if (a[i] == 0) {
      nxt[idx] = i;
      idx = i;
    }
  }
  bal = 0;
  for (i = 1; i <= n; i++) {
    bal += a[i];
    if (bal > d) die();
    if (a[i] == 0) {
      if (bal < 0) ans++;
      if (bal < 0) {
        bal = solve(i, nxt[i]);
        if (bal < 0) die();
      }
    }
  }
  cout << ans << endl;
}
