#include <cstdio>
#include <cstring>
#include <algorithm>
#define ll long long
#define inf 1<<30
#define il inline 
#define in1(a) read(a)
#define in2(a,b) in1(a),in1(b)
#define in3(a,b,c) in2(a,b),in1(c)
#define in4(a,b,c,d) in2(a,b),in2(c,d)
il void readl(ll &x){
    x=0;ll f=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')f=-f;c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    x*=f;
}
il void read(int &x){
    x=0;int f=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')f=-f;c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    x*=f;
}
using namespace std;
/*===================Header Template=====================*/
#define N 3005
int n,m;
int a[N]; 
int main(){
    int i,j,ans=0;
    in2(n,m);
    for(i=1;i<=n;i++) read(a[i]),a[i]+=a[i-1];
    for(i=1;i<=n;i++){
        for(j=max(1,i-m+1);j<=i;j++){
            ans=max(ans,a[i]-a[j-1]);
        }
    }
    printf("%d",ans);
    return 0;
}

#include<cstring>
#include<algorithm>
using namespace std;
int data[300003],f[300003],w[300003],x[300003];
int main(){
//  freopen("in.txt","r",stdin);
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    {
    scanf("%d",&data[i]);
    data[i]=data[i-1]+data[i];
    } 
    x[1]=0;w[1]=0;
    int head=1,tail=1;
    for(int i=1;i<=n;i++){
        if(x[head]<i-m) head++;
        f[i]=data[i]-data[x[head]];
        while(tail>=head&&data[i]<w[tail]) tail--;
        w[++tail]=data[i];x[tail]=i;
        
    }
    int res=-999999999;
    for(int i=1;i<=n;i++)
    res=max(f[i],res);
    printf("%d",res);
    return 0;
}```