#include<bits/stdc++.h>
#define forl(i,x,y) for(int i=x;i<=y;++i)
#define fort(i,x,y) for(int i=x;i>=y;--i)
using namespace std;
long long /*qword*/ a[10001]={0} , dp[10001]={-10e15} , maxdp[10001]={-10e15};
int main(){
   long long n, k ; cin>>n>>k;
    forl(i,1,n) cin>>a[i]; 
    dp[0] =0;
    maxdp[0]=0;
    forl(i,1,n){
        long long mx = -10e15;
        for(long long j= 1  ;j<=k && i-j>=0 ;j++ )
            mx = max (mx , dp[i-j]);
        dp[i] = mx + a[i];
        maxdp[i] = max (maxdp[i-1] , dp[i]);
    }
    cout<<( maxdp[n]>0 ? maxdp[n] : 0 )<<endl; // in kết quả
 
}

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