#include<bits/stdc++.h>
using namespace std;
 
int main(){
	int n ; cin>>n;
	vector<int>arr(n);
	for(int i = 0 ; i <n ; i++){
		cin>>arr[i];
	}
	vector<int>prefix(n); // declare a prefix array 
	prefix[0]=arr[0];
	for(int i =1 ; i< n ; i++){
		prefix[i]=prefix[i-1]+arr[i];
	}
	vector<int>suffix(n);
	suffix[n-1]=arr[n-1];
	for(int i = n-2; i>=0;i--){
		suffix[i]=suffix[i+1]+arr[i];
	}
	int b; cin>>b ;
    int max_sum =INT_MIN;
	for(int k = 0 ; k<=b;k++){
		int sum = 0; 
		if(k==0) sum = suffix[n-(b-k)];
		else sum = prefix[k-1] + suffix[n-(b-k)];
		max_sum=max(max_sum,sum);
	}
 
 
	cout<<max_sum;
	return 0 ; 
}
 
 

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