#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cout << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
long long int advceil(long long int num, long long int den) {
  return (num % den == 0 ? num / den : num / den + 1);
}
long long int lstbt(long long int val) {
  long long int msk = val & (val - 1);
  return log2(val ^ msk);
}
long long int modmul(long long int a, long long int b) {
  if (a < 1e9 and b < 1e9) return (a * b) % 1000000007;
  a %= 1000000007;
  b %= 1000000007;
  long long int res = 0;
  while (b > 0) {
    if (b & 1) res = (res + a) % 1000000007;
    a = (a * 2) % 1000000007;
    b /= 2;
  }
  return res;
}
long long int modexpo(long long int a, long long int b) {
  long long int res = 1;
  while (b > 0) {
    if (b & 1) res = modmul(res, a);
    a = modmul(a, a);
    b /= 2;
  }
  return res;
}
long long int gcd(long long int a, long long int b) {
  return a == 0 ? b : gcd(b % a, a);
}
vector<long long int> CALCfactor(long long int n) {
  vector<long long int> factor(n + 2, 0);
  for (long long int i = 4; i <= n; i += 2) factor[i] = 2;
  for (long long int j = 3; j <= n; j += 2) {
    if (factor[j]) continue;
    for (long long int i = 2 * j; i <= n; i += j) factor[i] = j;
  }
  return factor;
}
vector<long long int> CALCprimeNUM(long long int n) {
  vector<long long int> factor = CALCfactor(n);
  vector<long long int> primeNUM;
  primeNUM.reserve(n + 2);
  for (long long int i = 2; i <= n; i++)
    if (!factor[i]) primeNUM.push_back(i);
  return primeNUM;
}
vector<long long int> CALCprimeFACTOR(long long int n) {
  vector<long long int> factor = CALCfactor(n);
  vector<long long int> ans;
  while (factor[n] != 0) {
    ans.push_back(factor[n]);
    n /= factor[n];
  }
  if (n > 1) ans.push_back(n);
  return ans;
}
vector<long long int> unique(vector<long long int> x) {
  sort(x.begin(), x.end());
  set<long long int> s;
  vector<long long int> ans;
  ans.reserve(x.size());
  for (auto elem : x) s.insert(elem);
  for (auto elem : s) ans.push_back(elem);
  return ans;
}
pair<vector<long long int>, vector<long long int> > getFact(long long int n) {
  vector<long long int> fact(n + 1, 1), invfact(n + 1, 1);
  for (long long int i = 1; i <= n; i++)
    fact[i] = (i * (fact[i - 1])) % 1000000007;
  for (long long int i = 1; i <= n; i++)
    invfact[i] = (modexpo(i, 1000000007 - 2) * invfact[i - 1]) % 1000000007;
  return {fact, invfact};
}
void compress(vector<long long int>& arr, long long int n) {
  map<long long int, vector<long long int> > pos;
  for (long long int i = 1; i <= n; i++) pos[arr[i]].push_back(i);
  long long int cnt = 1;
  for (auto itr : pos) {
    for (auto elem : itr.second) arr[elem] = cnt;
    cnt++;
  }
}
bool rcomp(long long int a, long long int b) { return a > b; }
void solve() {
  long long int n, k;
  cin >> n >> k;
  vector<long long int> arr(n + 2, 0);
  for (long long int i = 1; i <= n; i++) cin >> arr[i];
  vector<long long int> pref(n + 2, 0), suff(n + 2, -1e12);
  for (long long int i = 1; i <= n; i++) {
    pref[i] = pref[i - 1] + arr[i];
    if (pref[i] > k) {
      cout << "-1"
           << "\n";
      return;
    }
  }
  for (long long int i = n + 1 - 1; i >= 1; i--)
    suff[i] = max(suff[i + 1], pref[i]);
  vector<long long int> zeropos;
  for (long long int i = 1; i <= n; i++)
    if (arr[i] == 0) zeropos.push_back(i);
  long long int ans = 0, profit = 0;
  vector<long long int> set;
  for (auto elem : zeropos) {
    if (pref[elem] + profit >= 0) continue;
    ans++;
    long long int profithere = abs(pref[elem] + profit);
    long long int maxval = max(0ll, k - suff[elem] - profit);
    if (maxval >= profithere)
      profit += maxval;
    else {
      cout << "-1"
           << "\n";
      return;
    }
  }
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  auto start1 = high_resolution_clock::now();
  solve();
  auto stop1 = high_resolution_clock::now();
  auto duration = duration_cast<microseconds>(stop1 - start1);
}

### Prompt

Generate a CPP solution to the following problem:

Recenlty Luba got a credit card and started to use it. Let's consider n consecutive days Luba uses the card.

She starts with 0 money on her account.

In the evening of i-th day a transaction ai occurs. If ai > 0, then ai bourles are deposited to Luba's account. If ai < 0, then ai bourles are withdrawn. And if ai = 0, then the amount of money on Luba's account is checked.

In the morning of any of n days Luba can go to the bank and deposit any positive integer amount of burles to her account. But there is a limitation: the amount of money on the account can never exceed d.

It can happen that the amount of money goes greater than d by some transaction in the evening. In this case answer will be «-1».

Luba must not exceed this limit, and also she wants that every day her account is checked (the days when ai = 0) the amount of money on her account is non-negative. It takes a lot of time to go to the bank, so Luba wants to know the minimum number of days she needs to deposit some money to her account (if it is possible to meet all the requirements). Help her!

Input

The first line contains two integers n, d (1 ≤ n ≤ 105, 1 ≤ d ≤ 109) —the number of days and the money limitation.

The second line contains n integer numbers a1, a2, ... an ( - 104 ≤ ai ≤ 104), where ai represents the transaction in i-th day.

Output

Print -1 if Luba cannot deposit the money to her account in such a way that the requirements are met. Otherwise print the minimum number of days Luba has to deposit money.

Examples

Input

5 10
-1 5 0 -5 3


Output

0


Input

3 4
-10 0 20


Output

-1


Input

5 10
-5 0 10 -11 0


Output

2

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cout << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
long long int advceil(long long int num, long long int den) {
  return (num % den == 0 ? num / den : num / den + 1);
}
long long int lstbt(long long int val) {
  long long int msk = val & (val - 1);
  return log2(val ^ msk);
}
long long int modmul(long long int a, long long int b) {
  if (a < 1e9 and b < 1e9) return (a * b) % 1000000007;
  a %= 1000000007;
  b %= 1000000007;
  long long int res = 0;
  while (b > 0) {
    if (b & 1) res = (res + a) % 1000000007;
    a = (a * 2) % 1000000007;
    b /= 2;
  }
  return res;
}
long long int modexpo(long long int a, long long int b) {
  long long int res = 1;
  while (b > 0) {
    if (b & 1) res = modmul(res, a);
    a = modmul(a, a);
    b /= 2;
  }
  return res;
}
long long int gcd(long long int a, long long int b) {
  return a == 0 ? b : gcd(b % a, a);
}
vector<long long int> CALCfactor(long long int n) {
  vector<long long int> factor(n + 2, 0);
  for (long long int i = 4; i <= n; i += 2) factor[i] = 2;
  for (long long int j = 3; j <= n; j += 2) {
    if (factor[j]) continue;
    for (long long int i = 2 * j; i <= n; i += j) factor[i] = j;
  }
  return factor;
}
vector<long long int> CALCprimeNUM(long long int n) {
  vector<long long int> factor = CALCfactor(n);
  vector<long long int> primeNUM;
  primeNUM.reserve(n + 2);
  for (long long int i = 2; i <= n; i++)
    if (!factor[i]) primeNUM.push_back(i);
  return primeNUM;
}
vector<long long int> CALCprimeFACTOR(long long int n) {
  vector<long long int> factor = CALCfactor(n);
  vector<long long int> ans;
  while (factor[n] != 0) {
    ans.push_back(factor[n]);
    n /= factor[n];
  }
  if (n > 1) ans.push_back(n);
  return ans;
}
vector<long long int> unique(vector<long long int> x) {
  sort(x.begin(), x.end());
  set<long long int> s;
  vector<long long int> ans;
  ans.reserve(x.size());
  for (auto elem : x) s.insert(elem);
  for (auto elem : s) ans.push_back(elem);
  return ans;
}
pair<vector<long long int>, vector<long long int> > getFact(long long int n) {
  vector<long long int> fact(n + 1, 1), invfact(n + 1, 1);
  for (long long int i = 1; i <= n; i++)
    fact[i] = (i * (fact[i - 1])) % 1000000007;
  for (long long int i = 1; i <= n; i++)
    invfact[i] = (modexpo(i, 1000000007 - 2) * invfact[i - 1]) % 1000000007;
  return {fact, invfact};
}
void compress(vector<long long int>& arr, long long int n) {
  map<long long int, vector<long long int> > pos;
  for (long long int i = 1; i <= n; i++) pos[arr[i]].push_back(i);
  long long int cnt = 1;
  for (auto itr : pos) {
    for (auto elem : itr.second) arr[elem] = cnt;
    cnt++;
  }
}
bool rcomp(long long int a, long long int b) { return a > b; }
void solve() {
  long long int n, k;
  cin >> n >> k;
  vector<long long int> arr(n + 2, 0);
  for (long long int i = 1; i <= n; i++) cin >> arr[i];
  vector<long long int> pref(n + 2, 0), suff(n + 2, -1e12);
  for (long long int i = 1; i <= n; i++) {
    pref[i] = pref[i - 1] + arr[i];
    if (pref[i] > k) {
      cout << "-1"
           << "\n";
      return;
    }
  }
  for (long long int i = n + 1 - 1; i >= 1; i--)
    suff[i] = max(suff[i + 1], pref[i]);
  vector<long long int> zeropos;
  for (long long int i = 1; i <= n; i++)
    if (arr[i] == 0) zeropos.push_back(i);
  long long int ans = 0, profit = 0;
  vector<long long int> set;
  for (auto elem : zeropos) {
    if (pref[elem] + profit >= 0) continue;
    ans++;
    long long int profithere = abs(pref[elem] + profit);
    long long int maxval = max(0ll, k - suff[elem] - profit);
    if (maxval >= profithere)
      profit += maxval;
    else {
      cout << "-1"
           << "\n";
      return;
    }
  }
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  auto start1 = high_resolution_clock::now();
  solve();
  auto stop1 = high_resolution_clock::now();
  auto duration = duration_cast<microseconds>(stop1 - start1);
}

```