#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long int
const int MOD = 1000000007;
const int MOD2 = 998244353;
const int INF = LLONG_MAX / 2;
const int MAXN = 100000;
int primes[1000000];
/*void seive() {
fill(primes, primes + 1000000, 1);
primes[0] = primes[1] = 0;
for (int i = 2; i * i < 1000000; i++) {
if (primes[i]) {
for (int j = i * i; j < 1000000; j += i) {
primes[j] = 0;
}
}
}
}
bool isPrime(int n) {
if (n <= 1) return false;
for (int i = 2; i * i <= n; i++) {
if (n % i == 0) return false;
}
return true;
}
int gcd(int a, int b) {
if (a == 0) return b;
return gcd(b % a, a);
}*/
int power(int a, int b, int mod) {
int res = 1;
a %= mod;
while (b > 0) {
if (b & 1) res = res * a % mod;
a = a * a % mod;
b >>= 1;
}
return res;
}
// nCr % MOD for n < MOD
int nCrModP(int n, int r) {
if (r > n) return 0;
if (r == 0 || r == n) return 1;
int numerator = 1, denominator = 1;
for (int i = 0; i < r; i++) {
numerator = (numerator * (n - i)) % MOD;
denominator = (denominator * (i + 1)) % MOD;
}
return (numerator * power(denominator, MOD - 2, MOD)) % MOD;
}
// Lucas's Theorem
int lucas(int n, int r) {
if (r == 0) return 1;
return (lucas(n / MOD, r / MOD) * nCrModP(n % MOD, r % MOD)) % MOD;
}
void solve() {
int n,k;
cin>>n>>k;
int A[n];
for(int i = 0 ; i<n ; i++){
cin>>A[i];
}
int dp[n];
dp[0] = 0;
multiset<int>ms;
ms.insert(0);
for(int i = 1 ; i<n ; i++){
int d = *ms.begin();
dp[i] = A[i]+d;
ms.insert(dp[i]);
if(ms.size()>k){
ms.erase(dp[i-k]);
}
}
cout<<dp[n-1]<<endl;
}
signed main() {
ios::sync_with_stdio(false); cin.tie(NULL);
//int t;
//cin >> t;
//while (t--) {
solve();
//}
return 0;
}
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