#include <bits/stdc++.h>
using ll = long long;
#define endl '\n'
#define fi first
#define sec second
#define pb push_back
#define sz(v) (int)(v).size()
#define all(v) (v).begin(), (v).end()
using namespace std;
const int maxn = (int)1e5;
int a[maxn + 5];
ll dp[maxn + 5];
deque<int> dq;
int n, k;
int main(){
// YEU CAM TU :>
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> k;
for(int i = 1; i <= n; i++){
cin >> a[i];
}
dq.push_back(0);
for(int i = 1; i <= n; i++){
while(!dq.empty() && dq.front() < i - k) dq.pop_front();
dp[i] = dp[dq.front()] + a[i];
while(!dq.empty() && dp[dq.back()] >= dp[i]) dq.pop_back();
dq.push_back(i);
}
ll ans = 0, total = accumulate(a + 1, a + n + 1, 0LL);
for(int i = n - k + 1; i <= n; i++){
ans = max(ans, total - dp[i]);
}
cout << ans;
return 0;
}
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