#include<stdio.h>
#define MAX 999999999
int n,k,v[50002],max=-MAX,var;
void read()
{
	FILE*f=fopen("secv2.in","r");
	fscanf(f,"%d%d",&n,&k);
	int i=1,min,j;
	for(;i<=n;++i)
	{
		fscanf(f,"%d",&v[i]);
		
		v[i]+=v[i-1];
		var=v[i];
		min=MAX;
		for(j=i-k;j>=0;--j)
			if(v[j]<min)min=v[j];
		
		var-=min;
		if(var>max&&min!=MAX)max=var;
	}
	fclose(f);
}
int main()
{
	read();
	FILE*g=fopen("secv.out","w");
	fprintf(g,"%d",max);
	fclose(g);
	return 0;
}