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 <iostream>
#include <cmath>
#include <vector>
#include <stack>
#include <cstdio>
#include <string>
#include <bitset>
#include <list>
#include <set>
#include <algorithm>
#include <numeric>
#include <unordered_map>
#include <functional>
#include <queue>
#include <regex>
#include <cassert>
#include <map>
#include <type_traits>
#include <array>
#include <cassert>
#include <typeinfo>
#include <time.h>
//#include "boost/variant.hpp"

// #include "bits/stdc++.h"

using namespace std;



#define rep(i, N, M) for(ll i=N, i##_len=(M); i<i##_len; ++i)
#define rep_skip(i, N, M, ...) for(ll i=N, i##_len=(M); i<i##_len; i+=(skip))
#define rrep(i, N, M)  for(ll i=(M)-1, i##_len=(N-1); i>i##_len; --i)
#define pb push_back

typedef pair<double, double> pd;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> pll;
typedef tuple<ll, ll, ll> tll;
typedef tuple<ll, ll, ll, ll> tll4;
typedef tuple<ll, ll, ll, ll, ll> tll5;
typedef tuple<ll, ll, ll, ll, ll, ll> tll6;

typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<pll> vpll;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<string> vs;
template<typename T>
using pq_greater = priority_queue<T, vector<T>, greater<T>>;


#define all(a)  (a).begin(),(a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define vec(a) vector<a>
#define perm(c) sort(all(c));for(bool c##perm=1;c##perm;c##perm=next_permutation(all(c)))

template<typename T> void chmin(T &a, T b) {
	if (a > b) a = b;
}
template<typename T> void chmax(T &a, T b) {
	if (a < b) a = b;
}

vll seq(ll i, ll j) {
	vll res(j - i);
	rep(k, i, j) res[k] = i + k;
	return res;
}

constexpr ll POW_(ll n, ll m) {
	ll res = 1;
	rep(i, 0, m) {
		res *= n;
	}
	return res;
}

template<ll mod = 0>
constexpr ll POW(ll x, ll n) {
	if (x == 2)
	{
		return (1LL << n) % mod;
	}
	if (n == 0)return 1;
	if (n == 1)return x % mod;
	if (n % 2 == 0)return POW_(POW<mod>(x, n / 2), 2LL) % mod;
	return ((POW_(POW<mod>(x, n / 2), 2LL) % mod)*(x%mod)) % mod;
}
template<>
constexpr ll POW<0>(ll x, ll n) {
	if (x == 2)
	{
		return 1LL << n;
	}
	if (n == 0)return 1;
	if (n == 1)return x;
	if (n % 2 == 0) return POW_(POW(x, n / 2), 2);
	return (POW_(POW(x, n / 2), 2))*x;
}

template<ll mod>
constexpr ll Plus(ll x, ll y) {
	return (x + y) % mod;
}

template<ll mod>
constexpr ll Minus(ll x, ll y) {
	return (x + mod - y) % mod;
}

template<ll mod>
constexpr ll Prod(ll x, ll y) {
	return (x * y) % mod;
}

template<ll mod>
constexpr ll Inv(ll x) {
	assert(x%mod != 0);
	return POW<mod>(x, mod - 2);
}

template<ll mod>
constexpr ll Dev(ll x, ll y) {
	return x * Inv<mod>(y);
}


template<ll bit = 2LL>
ll at_bit(ll n, ll i) {
	return n / POW(bit, i) % bit;
}

template<>
ll at_bit<2>(ll n, ll i) {
	return (n >> i) % 2LL;
}

template<ll bit>
ll get_bit(ll i) {
	return POW(bit, i);
}

template<>
ll get_bit<2>(ll i) {
	return 1LL << i;
}

template<ll bit = 2>
ll get_max_bit(ll n) {
	ll tmp = bit;
	ll at = 0;
	while (tmp <= n) {
		at++;
		tmp *= bit;
	}
	return at;
}

template<>
ll get_max_bit<2>(ll n) {
	ll tmp = 2;
	ll at = 0;
	while (tmp <= n) {
		at++;
		tmp <<= 1;
	}
	return at;
}

vll getDivisors(ll n) {
	vll res;
	ll i = 1;

	for (; i*i < n; i++) {
		if (n%i == 0) {
			res.push_back(i);
			res.push_back(n / i);
		}
	}
	if (i*i == n)res.push_back(i);
	sort(res.begin(), res.end());
	return res;
}

vll getDivisors(ll n, ll m) {
	if (n > m) swap(n, m);
	vll res;
	ll i = 1;

	for (; i*i < n; i++) {
		if (n%i == 0) {
			if (m%i == 0) res.push_back(i);
			if (m % (n / i) == 0) res.push_back(n / i);
		}
	}
	if (i*i == n) if (m%i == 0) res.push_back(i);
	sort(res.begin(), res.end());
	return res;
}


ll gcd(ll a, ll b) {
	if (a%b == 0) return b;
	else return gcd(b, a%b);
}

template<
	typename Inputs,
	typename Functor,
	typename T = typename Inputs::value_type>
	void sort_by(Inputs& inputs, Functor f) {
	std::sort(std::begin(inputs), std::end(inputs),
		[&f](const T& lhs, const T& rhs) { return f(lhs) < f(rhs); });
}

template<
	typename Inputs,
	typename Functor,
	typename T = typename Inputs::value_type>
	void stable_sort_by(Inputs& inputs, Functor f) {
	std::stable_sort(std::begin(inputs), std::end(inputs),
		[&f](const T& lhs, const T& rhs) { return f(lhs) < f(rhs); });
}

// Functor is expected to be functional<val ,bool>
// This function returns the maximum iterator that stisfies f(*it) == f(* inputs.begin())
template<
	typename Inputs,
	typename Functor,
	typename ValType = typename Inputs::value_type>
	pair<typename Inputs::iterator, typename Inputs::iterator> binary_solve(Inputs& inputs, Functor f)
{

	auto left = inputs.begin();
	auto right = inputs.end();
	auto n = inputs.size();

	auto left_val = f(*left);
	auto right_val = f(*(right - 1));

	// check 
	assert(n >= 2);
	assert(left_val != right_val);

	while (left + 1 != right)
	{
		auto mid = left + (right - left) / 2;
		if (f(*mid) == left_val)
		{
			left = mid;
		}
		else
		{
			right = mid;
		}
	}

	return { left,right };
}

template<typename T>
bool check_binary_solve(T left, T right) {
	return left != right;
}
template<>
bool check_binary_solve<double>(double left, double right) {
	return abs(left - right) > 0.0000000000001;
}

template<typename T, typename Functor>
	pair<T, T > binary_solve(T left, T right, Functor f)
{
	auto left_val = f(left);
	auto right_val = f(right);

	// check 
	assert(left < right);
	if (right_val == left_val)
		throw invalid_argument("right_val == left_val");

	while (check_binary_solve<T>(left, right))
	{
		auto mid = left + (right - left) / 2;
		if (f(mid) == left_val)
		{
			left = mid;
		}
		else
		{
			right = mid;
		}
	}

	return { left,right };
}


template<int I>
vll proj(vpll v) {
	vll res(v.size());
	rep(i, 0, v.size()) {
		if (!I) res[i] = v[i].first;
		else res[i] = v[i].second;
	}
	return res;
}


template<int I, class T>
vll proj(T v) {
	vll res(v.size());
	rep(i, 0, v.size()) {
		res[i] = get<I>(v[i]);
	}
	return res;
}
vector<pll >prime_factorize(ll n) {
	vector<pll> res;
	for (ll p = 2; p*p <= n; ++p) {
		if (n%p != 0)continue;
		ll num = 0;
		while (n%p == 0) { ++num; n /= p; }
		res.push_back({ p,num });
	}
	if (n != 1) res.push_back(make_pair(n, 1));
	return res;
}


constexpr ll MOD = 1000000007;
constexpr ll INF = 1LL << 62;

template <typename Monoid>
struct segment_tree
{

	using underlying_type = typename  Monoid::underlying_type;

	segment_tree(ll a_n) : size_original(a_n)
	{
		vector<underlying_type> initial_value = vector<underlying_type>(a_n, Monoid::unit());
		segment_tree_impl(a_n, initial_value);
	}

	segment_tree(ll a_n, vector<underlying_type>& initial_value) : size_original(a_n)
	{
		segment_tree_impl(a_n, initial_value);
	}

	void update(int i, underlying_type z) { // 0-based
		assert(0 <= i && i < 2 * n - 1);
		a[i + n - 1] = z;
		for (i = (i + n) / 2; i > 0; i /= 2) { // 1-based
			a[i - 1] = Monoid::append(a[2 * i - 1], a[2 * i]);
		}
	}

	underlying_type query(ll l, ll r) { // 0-based, [l, r)
		underlying_type lacc = Monoid::unit(), racc = Monoid::unit();
		assert(l <= r && r <= n);
		l += n; r += n;
		for (; l < r; l /= 2, r /= 2) { // 1-based loop, 2x faster than recursion
			if (l % 2 == 1) lacc = Monoid::append(lacc, a[(l++) - 1]);
			if (r % 2 == 1) racc = Monoid::append(a[(--r) - 1], racc);
		}
		return Monoid::append(lacc, racc);
	}

	ll size() { return size_original; }

private:
	ll size_original;
	ll n;
	vector<underlying_type> a;
	void segment_tree_impl(ll a_n, vector<underlying_type>& initial_value)
	{
		assert(a_n == initial_value.size());
		n = 1; while (n < a_n) n *= 2;
		a.resize(2 * n - 1, Monoid::unit());
		rep(i, 0, initial_value.size()) {
			a[i + (n - 1)] = initial_value[i];
		}
		rrep(i, 0, n - 1) a[i] = Monoid::append(a[2 * i + 1], a[2 * i + 2]); // propagate initial values
	}
};


template <typename T>
struct min_indexed_t {
	typedef pair<T, ll> underlying_type;
	static underlying_type make_indexed(vector<T> v)
	{
		underlying_type w(v.size());
		rep(i, 0, v.size()) {
			w[i] = { v[i],i };
		}
		return w;
	}
	static underlying_type unit() { return make_pair(numeric_limits<T>::max(), -1); }
	static underlying_type append(underlying_type a, underlying_type b) { return min(a, b); }
};
template <typename T>
struct min_t {
	typedef T underlying_type;
	static underlying_type unit() { return numeric_limits<T>::max(); }
	static underlying_type append(underlying_type a, underlying_type b) { return min(a, b); }
};

struct linear_t {
	typedef pd underlying_type;
	static underlying_type unit() { return underlying_type{ 1.,0. }; }
	static underlying_type append(underlying_type a, underlying_type b) {
		return underlying_type{ a.first*b.first, b.first*a.second + b.second };
	}
};



vll get_topologically_sorted_nodes(const vvll& graph)
{
	// graph needs to be represented by adjacent list.
	// complexity: O( node size + edge size)
	ll nodeSize = graph.size();

	// find root
	vll roots;
	vll inDegree(nodeSize);
	rep(i, 0, nodeSize)
	{
		for (ll sibling : graph[i]) {
			inDegree[sibling]++;
		}
	}

	rep(i, 0, nodeSize) {
		if (inDegree[i] == 0) {
			roots.push_back(i);
		}
	}

	stack<ll> parents;
	for (ll i : roots)
		parents.push(i);

	vll sortedNodes;
	while (!parents.empty()) {
		ll parent = parents.top();
		parents.pop();
		sortedNodes.push_back(parent);
		for (ll sibling : graph[parent]) {
			inDegree[sibling]--;
			if (inDegree[sibling] == 0) {
				parents.push(sibling);
			}
		}
	}
	return sortedNodes;
}

struct UnionFind {
	vector<ll> data;
	vll querySize_;
	set<ll> roots;
	UnionFind(ll size) : data(size, -1), querySize_(size, 0) {
		rep(i, 0, size) roots.insert(i);
	}

	ll unite(ll x, ll y) {
		// return: root
		x = operator[](x); y = operator[](y);
		if (x != y) {
			if (data[y] < data[x]) swap(x, y);
			data[x] += data[y]; data[y] = x;
			querySize_[x] += querySize_[y] + 1;
			roots.erase(y);
			return x;
		}
		else {
			querySize_[x]++;
			return x;
		}
	}
	bool is_same(ll x, ll y) {
		// check whether x and y are connected
		return operator[](x) == operator[](y);
	}
	ll operator[](ll x) {
		// get root
		return data[x] < 0 ? x : data[x] = operator[](data[x]);
	}
	ll size(ll x) {
		return -data[operator[](x)];
	}
	ll  query_size(ll x) {
		return querySize_[operator[](x)];
	}
	const set<ll>& getRoots() {
		return roots;
	}
	ll rank(ll x) {
		return -data[operator[](x)];
	}
	void initialize() {
		for (auto& i : data) {
			i = -1;
		}
	}
};
#include <iomanip>
int dx[4] = { 0, 1, 0, -1 }, dy[4] = { -1, 0, 1, 0 };
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	ll n, k;
	cin >> n >> k;
	vll a(n);
	rep(i, 0, n) {
		cin >> a[i];

	}
	
	vll res(1,0);
	vll S(n + 1);
	rep(i, 0, n) {
		S[i + 1] = S[i] + a[i];
	}
	rep(i, 0, n - k+1) {
		ll x=0;
		rep(j, 0, n) {
			if (j < i || i+k <= j) {
				x += max(0LL,a[j]);
			}
		}
			x +=max( accumulate(a.begin() + i, a.begin() + i + k, 0LL),0LL);
		res.push_back(x);
	}


	cout <<  *max_element(all(res));

	return 0;
}

