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 <vector>
#include <deque>
#include <algorithm>
#include <numeric>
#include <string>
#include <cstring>
#include <list>
#include <unordered_set>
#include <tuple>
#include <cmath>
#include <limits>
#include <type_traits>
#include <iomanip>
#include <map>
#include <unordered_map>
#include <queue>
#include <stack>
#include <set>
#include <bitset>
#include <regex>
using namespace std;

#define rep(i,n)	for(lint i = 0; i < n; i++)
#define repr(i,n)	for(lint i = n - 1; i >= 0; i--)
#define repi(i,ini,n)	for(lint i = ini; i < n; i++)
#define repir(i,ini,n)	for(lint i = n-1; i >= ini; i--)
#define repb(i,start,end)	for(lint i = start; i <= end; i++)
#define repbr(i,start,end)	for(lint i = end; i >= start; i--)

#define bit(n)				(1LL << n)
#define brep(i, n)			rep(i, bit(n))
#define brepi(i, ini, n)	repi(i, ini, bit(n))

#define len(a)	(static_cast<lint>(a.size()))

#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define rg(v, n) v.begin(), v.begin()+n
#define rrg(v, n) v.rbegin(), v.rbegin()+n

#define ret return 0;

namespace {

	using lint = long long;
	using ulint = unsigned long long;
	using ld = long double;
	struct xy
	{
		lint x, y;
		xy() :x(0), y(0) {}
		xy(lint _x, lint _y) : x(_x), y(_y) {}
		xy operator+(const xy& p) const
		{
			return xy(x + p.x, y + p.y);
		}
		bool operator<(xy p) const
		{
			if (y == p.y)
				return x < p.x;
			return y < p.y;
		}
	};
	struct xyd
	{
		ld x, y;
		xyd() :x(0), y(0) {}
		xyd(long double _x, long double _y) : x(_x), y(_y) {}
	};
	using vec = vector<lint>;
	using vecd = vector<ld>;
	using vecs = vector<string>;
	using vecp = vector<xy>;
	template<class T> using vect = vector<T>;
	class vec2 : public vector<vector<lint>>
	{
	public:
		vec2() {}
		vec2(lint n) : vector(n) {}
		vec2(lint h, lint w) : vector(h, vector<lint>(w)) {}
		vec2(lint h, lint w, lint v) : vector(h, vector<lint>(w, v)) {}
	};

	template<class T> using priq = priority_queue<T>;
	template<class T> using rpriq = priority_queue<T, vector<T>, greater<T>>;
	template<class Key, class Val> using hashmap = unordered_map<Key, Val>;
	template<class Key> using hashset = unordered_set<Key>;

	const ulint mod = 1000000007;
	//const ulint mod = 998244353;
	const double pi = 3.141592653589793238462;
	const lint intmax = 9223372036854775807;
	const lint inf = 1100100100100100100LL;
	const ld eps = 0.0000001;
	const lint alpn = 'z' - 'a' + 1;

	template<class T>
	constexpr auto msum(T arg0)
	{
		return arg0;
	}

	template<class T, class ...Types>
	constexpr auto msum(T arg0, Types ...args)
	{
		static_assert(sizeof...(args) > 0, "arg err");

		return arg0 + msum(args...);
	}

	template<class It>
	constexpr typename It::value_type mmax(It begin, It end)
	{
		return *max_element(begin, end);
	}

	template<class It>
	constexpr typename It::value_type mmin(It begin, It end)
	{
		return *min_element(begin, end);
	}

	template<class T>
	constexpr auto mmax(T arg)
	{
		return arg;
	}

	template<class T, class ...Types>
	constexpr auto mmax(T arg0, Types ...args)
	{
		using promote_t = decltype(msum(arg0, args...));

		return max(static_cast<promote_t>(arg0), static_cast<promote_t>(mmax(args...)));
	}

	template<class T>
	constexpr auto mmin(T arg)
	{
		return arg;
	}

	template<class T, class ...Types>
	constexpr auto mmin(T arg0, Types ...args)
	{
		using promote_t = decltype(msum(arg0, args...));

		return min(static_cast<promote_t>(arg0), static_cast<promote_t>(mmin(args...)));
	}

	template<class T>
	struct Mplus
	{
		T operator()(const T& a, const T& b)
		{
			return a + b;
		}

		const static T id = T(0);
	};

	template<
		class It,
		class T = typename It::value_type,
		class Monoid = Mplus<T>>
		T acc(It begin, It end, Monoid f = Mplus<T>())
	{
		return accumulate(begin, end, Monoid::id, f);
	}

	constexpr auto clamp(lint val, lint left, lint right)
	{
		return mmax(mmin(val, right), left);
	}

	constexpr lint div2(lint p, lint q)
	{
		return (p + q - 1) / q;
	}

#if(__cplusplus < 201703L)

	lint gcd(lint a, lint b) {
		while (1) {
			if (a < b) swap(a, b);
			if (!b) break;
			a %= b;
		}
		return a;
	}

	lint lcm(lint a, lint b)
	{
		return a / gcd(a, b) * b;
	}

#endif

	lint powInt(lint a, lint b)
	{
		if (b == 0)
		{
			return 1;
		}
		if (b == 1)
		{
			return a;
		}
		lint tmp = powInt(a, b / 2);
		return (b % 2 == 1 ? a * tmp * tmp : tmp * tmp);
	}

	template<class T>
	T sgn(T val)
	{
		if (val == T(0))
			return T(0);
		if (val < 0)
			return T(-1);
		if (val > 0)
			return T(1);
	}

	template<class T>
	constexpr auto modK_belowN(T k, T MOD, T n)
	{
		return (n + MOD - k - 1) / MOD;
	}

	template<class It, class T>
	bool exist(It begin, It end, const T& val)
	{
		return find(begin, end, val) != end;
	}

	template<class It, class Pr>
	bool exist_if(It begin, It end, Pr pred)
	{
		return find_if(begin, end, pred) != end;
	}

	template<class T>
	bool between(T val, T l, T r)
	{
		return (val >= l) && (val <= r);
	}

	template<class It>
	auto carr(It begin, It end) {
		vec c;
		c.push_back(1);
		auto before = *begin;
		for (auto it = begin + 1; it != end; it++) {
			if (before != *it) {
				c.push_back(0);
				before = *it;
			}
			c.back()++;
		}
		return c;
	}

	template<class T>
	struct nval {
		lint n;
		T val;
		nval() : n(0) {};
		nval(lint _n, T _val) : n(_n), val(_val) {};
	};

	template<class It>
	auto carr2(It begin, It end) {
		using T = nval<remove_reference_t<decltype(*begin)>>;

		vect<T> c;
		c.push_back(T(1, *begin));
		auto before = *begin;
		for (auto it = begin + 1; it != end; it++) {
			if (before != *it) {
				c.push_back(T(0, *it));
				before = *it;
			}
			c.back().n++;
		}
		return c;
	}

	template<class It, class ...T>
	void sort2(It begin, It end, T ...p)
	{
		using val_t = remove_reference_t<decltype(*begin)>;

		sort(begin, end, [p...](const val_t& a, const val_t& b) {
			bool neq[] = { (a.*p != b.*p)... };
			bool sg[] = { (a.*p < b.*p)... };

			rep(i, sizeof...(p)) {
				if (neq[i])
				{
					return sg[i];
				}
			}
			return false;
		});
	}

	template<size_t _K, size_t _N, class ...Types, size_t ...indices>
	auto constexpr __ModKtuple_Impl(index_sequence<indices...>, tuple<Types...> args)
	{
		return make_tuple(get<indices* _N + _K>(args)...);
	}

	template<size_t K, size_t N, class ...Types>
	auto constexpr ModKtuple(Types ...args)
	{
		return __ModKtuple_Impl<K, N>(make_index_sequence<modK_belowN(K, N, sizeof...(args))>{}, forward_as_tuple(args...));
	}

	template<class It, class ...T, class ...Tsg, size_t ...indices>
	void __sort3_Impl(It begin, It end, tuple<T...> p, tuple<Tsg...> sgf, index_sequence<indices...>)
	{
		using val_t = remove_reference_t<decltype(*begin)>;

		sort(begin, end, [p, sgf](val_t a, val_t b) {
			bool neq[] = { (a.*(get<indices>(p)) != b.*(get<indices>(p)))... };
			bool sg[] = { ((a.*(get<indices>(p)) < b.*(get<indices>(p))) != (get<indices>(sgf))) ... };

			rep(i, sizeof...(indices)) {
				if (neq[i])
				{
					return sg[i];
				}
			}
			return false;
			});
	}

	template<class It, class ...T>
	void sort3(It begin, It end, T ...p)
	{
		using val_t = remove_reference_t<decltype(*begin)>;

		auto p_forward = ModKtuple<0, 2>(p...);
		auto sgf_forward = ModKtuple<1, 2>(p...);

		constexpr auto p_sz = tuple_size<decltype(p_forward)>::value;
		constexpr auto sgf_sz = tuple_size<decltype(sgf_forward)>::value;

		static_assert(p_sz == sgf_sz, "arg err");

		__sort3_Impl(begin, end, p_forward, sgf_forward, make_index_sequence<p_sz>{});
	}

	template<class It, class It2>
	auto spacel(It i, It2 end)
	{
		if (i + 1 == end)
		{
			return '\n';
		}
		else
		{
			return ' ';
		}
	}

	bool match(string s, string r)
	{
		return regex_match(s, regex(r));
	}

	template<class It>
	bool next_comb(lint n, It begin, It end)
	{
		auto rend = make_reverse_iterator(begin);
		auto rbegin = make_reverse_iterator(end);

		auto rit = rbegin;
		for (; rit != rend; rit++)
		{
			if ((rit == rbegin && (*rit) + 1 != n) ||
				(rit != rbegin && (*rit) + 1 != *(rit - 1)))
			{
				goto found;
			}
		}
		return false;
	found:;
		(*rit)++;

		for (auto it = rit.base(); it != end; it++)
		{
			(*it) = (*(it - 1)) + 1;
		}
		return true;
	}

	ostream& setp(ostream& ost)
	{
		cout << setprecision(60) << fixed;
		return ost;
	}

#ifdef _LOCAL
	auto& dbg = cout;
#else
	struct dummy_cout
	{
		template<class T>
		dummy_cout& operator<<(T&& op)
		{
			return *this;
		}

		using endl_t = basic_ostream<char, char_traits<char>>;

		dummy_cout& operator<<(endl_t& (*)(endl_t&))
		{
			return *this;
		}
	};

	dummy_cout dbg;
#endif
};

int main()
{
	lint n, k;
	cin >> n >> k;
	vec a(n);
	rep(i, n)
		cin >> a[i];

	vec as(n + 1);
	as[0] = 0;
	rep(i, n)
		as[i + 1] = as[i] + a[i];

	vec ap(n + 1), apr(n + 1);
	ap[0] = apr[0] = 0;
	rep(i, n)
		ap[i + 1] = ap[i] + mmax(0, a[i]);
	rep(i, n)
		apr[i + 1] = ap[i] + mmax(0, a[n - i - 1]);

	lint ans = 0;
	rep(i, n - k + 1)
	{
		ans = mmax(ans, ap[i] + ap[n - i - k] + mmax(0, as[i+k] - as[i]));
	}

	cout << ans << endl;
	return 0;
}
