#include<cstdio>
int s[16010];
using namespace std;
int main()
{
    freopen("transport.in","r",stdin);
    freopen("transport.out","w",stdout);
    int n,k,i,j,max=0,p,v,last;
    scanf("%d%d",&n,&k);
    for(i=1;i<=n;i++)
        scanf("%d",&s[i]);
    max=s[1];
    last=1;
    for(i=2;i<=k;i++)
    {
        p=0;
        for(j=last;j<=i;j++)
            p=p+s[j];
        last=j-1;
        if(p>max)
            max=p;
    }
    printf("%d\n",max);
    return 0;
}