0pt

#include<cstdio>
#include<algorithm>
using namespace std;
long long n,k,a[100010],c[100010],wantac,temp;
int main(){
	scanf("%lld %lld",&n,&k);
	n--;
	for(int i=1;i<=n;i++){
		scanf("%lld",&a[i]);
		wantac+=a[i];
	}
	for(int i=1;i<=n;i++){
		c[i]=c[i-1]+a[i];
		if(i>k){
			c[i]-=c[i-k];		
		}
	}
	for(int i=2;i<=n;i++){
		for(int j=i;j>=2;j--){
			if(a[j-1]>a[j]){
				temp=a[j-1];
				a[j-1]=a[j];
				a[j]=temp;
			}
			else break;
		}
	}
	printf("%lld",wantac-c[n]);
}

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