#include <bits/stdc++.h>
using namespace std;
int maxSum(vector<int>nums,int k){
	int n=nums.size();
	int i=0;
	int j=0;
	int sum=0;
	int maxi=0;
	while(j<n){
		sum+=nums[j];
		if(j-i+1<k){
			j++;
		}else if(j-i+1==k){
				maxi=max(maxi,sum);
				sum-=nums[i];
				i++;
				j++;
			}
	}
	return maxi;
}
 
int main() {
	// your code goes here
	int n;
	cin>>n;
	vector<int>arr(n);
	for(int i=0;i<n;i++){
		cin>>arr[i];
	}
	int k;
	cin>>k;
	cout<<"The maximum sum is:"<<maxSum(arr,k);
	return 0;
}

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

NAoxMDAgMjAwIDMwMCA0MDAKMg==

4
100 200 300 400
2