There are N squares aligned in a row. The i-th square from the left contains an integer a_i.

Initially, all the squares are white. Snuke will perform the following operation some number of times:

* Select K consecutive squares. Then, paint all of them white, or paint all of them black. Here, the colors of the squares are overwritten.



After Snuke finishes performing the operation, the score will be calculated as the sum of the integers contained in the black squares. Find the maximum possible score.

Constraints

* 1≤N≤10^5
* 1≤K≤N
* a_i is an integer.
* |a_i|≤10^9

Input

The input is given from Standard Input in the following format:


N K
a_1 a_2 ... a_N


Output

Print the maximum possible score.

Examples

Input

5 3
-10 10 -10 10 -10


Output

10


Input

4 2
10 -10 -10 10


Output

20


Input

1 1
-10


Output

0


Input

10 5
5 -4 -5 -8 -4 7 2 -4 0 7


Output

17
#include <bits/stdc++.h>
template <typename T>
class IntegerIterator
    : public std::iterator<std::input_iterator_tag, T, std::ptrdiff_t, T*, T> {
 public:
  explicit IntegerIterator(T value) : value(value) {}
  IntegerIterator& operator++() {
    ++value;
    return *this;
  }
  IntegerIterator operator++(int) {
    IntegerIterator copy = *this;
    ++value;
    return copy;
  }
  IntegerIterator& operator--() {
    --value;
    return *this;
  }
  IntegerIterator operator--(int) {
    IntegerIterator copy = *this;
    --value;
    return copy;
  }
  T operator*() const { return value; }
  bool operator==(IntegerIterator rhs) const { return value == rhs.value; }
  bool operator!=(IntegerIterator rhs) const { return !(*this == rhs); }

 private:
  T value;
};
template <typename T>
class IntegerRange {
 public:
  IntegerRange(T begin, T end) : begin_(begin), end_(end) { ; }
  IntegerIterator<T> begin() const { return IntegerIterator<T>(begin_); }
  IntegerIterator<T> end() const { return IntegerIterator<T>(end_); }

 private:
  T begin_;
  T end_;
};
template <typename T>
class ReversedIntegerRange {
 public:
  ReversedIntegerRange(T begin, T end) : begin_(begin), end_(end) { ; }
  std::reverse_iterator<IntegerIterator<T>> begin() const {
    return std::reverse_iterator<IntegerIterator<T>>(
        IntegerIterator<T>(begin_));
  }
  std::reverse_iterator<IntegerIterator<T>> end() const {
    return std::reverse_iterator<IntegerIterator<T>>(IntegerIterator<T>(end_));
  }

 private:
  T begin_;
  T end_;
};
template <typename T>
IntegerRange<T> range(T to) {
  return IntegerRange<T>(0, to);
}
template <typename T>
IntegerRange<T> range(T from, T to) {
  return IntegerRange<T>(from, to);
}
template <typename T>
IntegerRange<T> inclusiveRange(T to) {
  return IntegerRange<T>(0, to + 1);
}
template <typename T>
IntegerRange<T> inclusiveRange(T from, T to) {
  return IntegerRange<T>(from, to + 1);
}
template <typename T>
ReversedIntegerRange<T> downrange(T from) {
  return ReversedIntegerRange<T>(from, 0);
}
template <typename T>
ReversedIntegerRange<T> downrange(T from, T to) {
  return ReversedIntegerRange<T>(from, to);
}
template <typename T>
ReversedIntegerRange<T> inclusiveDownrange(T from) {
  return ReversedIntegerRange<T>(from + 1, 0);
}
template <typename T>
ReversedIntegerRange<T> inclusiveDownrange(T from, T to) {
  return ReversedIntegerRange<T>(from + 1, to);
}
template <typename R>
void sort(R& range) {
  std::sort(range.begin(), range.end());
}
template <typename R, typename Comp>
void sort(R& range, Comp comp) {
  std::sort(range.begin(), range.end(), comp);
}
template <typename R>
void reverse(R& range) {
  std::reverse(range.begin(), range.end());
}
template <typename R, typename T>
auto lower_bound(const R& range, const T& value) -> decltype(range.begin()) {
  return std::lower_bound(range.begin(), range.end(), value);
}
template <typename R, typename T, typename Comp>
auto lower_bound(const R& range, const T& value, Comp comp)
    -> decltype(range.begin()) {
  return std::lower_bound(range.begin(), range.end(), value, comp);
}
template <typename R, typename T>
auto upper_bound(const R& range, const T& value) -> decltype(range.begin()) {
  return std::upper_bound(range.begin(), range.end(), value);
}
template <typename R, typename T, typename Comp>
auto upper_bound(const R& range, const T& value, Comp comp)
    -> decltype(range.begin()) {
  return std::upper_bound(range.begin(), range.end(), value, comp);
}
template <typename R>
auto min_element(const R& range) -> decltype(range.begin()) {
  return std::min_element(range.begin(), range.end());
}
template <typename R>
auto max_element(const R& range) -> decltype(range.begin()) {
  return std::max_element(range.begin(), range.end());
}
template <typename R>
bool next_permutation(R& range) {
  return std::next_permutation(range.begin(), range.end());
}
template <typename T>
void unique(std::vector<T>& range) {
  range.erase(std::unique(range.begin(), range.end()), range.end());
}
template <typename R>
R sorted(R range) {
  sort(range);
  return range;
}
template <typename R, typename Comp>
R sorted(R range, Comp comp) {
  sort(range, comp);
  return range;
}
template <typename R>
R reversed(R range) {
  reverse(range);
  return range;
}
template <typename T>
void updateMin(T& oldValue, const T& newValue) {
  if (newValue < oldValue) {
    oldValue = newValue;
  }
}
template <typename T>
void updateMax(T& oldValue, const T& newValue) {
  if (oldValue < newValue) {
    oldValue = newValue;
  }
}
template <typename T>
using range_iterator_traits = std::iterator_traits<
    typename std::decay<decltype(std::declval<T>().begin())>::type>;
template <typename R>
auto prefixSums(const R& range)
    -> std::vector<typename range_iterator_traits<R>::value_type> {
  std::vector<typename range_iterator_traits<R>::value_type> result(
      static_cast<std::size_t>(
          std::distance(std::begin(range), std::end(range)) + 1));
  std::partial_sum(std::begin(range), std::end(range), result.begin() + 1);
  return result;
}
using namespace std;
class TaskB {
 public:
  void solve(std::istream& in, std::ostream& out) {
    int n, k;
    in >> n >> k;
    vector<int64_t> v(n), u(n);
    for (int i : range(n)) {
      in >> v[i];
      u[i] = max<int64_t>(v[i], 0);
    }
    auto pu = prefixSums(u);
    auto pv = prefixSums(v);
    int64_t ans = (int64_t)-1e16;
    for (int i = 0; i + k <= n; ++i) {
      int64_t cur = pv[i + k] - pv[i] + pu[n] - pu[i + k] + pu[i];
      updateMax(ans, cur);
    }
    out << ans << "\n";
  }
};
int main() {
  std::ios_base::sync_with_stdio(false);
  TaskB solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  in.tie(nullptr);
  out << std::fixed;
  out.precision(20);
  solver.solve(in, out);
  return 0;
}
