/*Write a program to take an integer array arr and an integer k as inputs. Print the maximum sum of all the 
subarrays of size k.*/
#include <stdio.h>
 
int main() {
    int n, k;
    scanf("%d %d", &n, &k);
 
    int arr[n];
    for (int i = 0; i < n; i++)
        scanf("%d", &arr[i]);
 
    int sum = 0;
 
    // First window
    for (int i = 0; i < k; i++)
        sum += arr[i];
 
    int maxSum = sum;
 
    // Slide the window
    for (int i = k; i < n; i++) {
        sum += arr[i] - arr[i - k];  // add new, remove old
        if (sum > maxSum)
            maxSum = sum;
    }
 
    printf("%d", maxSum);
    return 0;
}
 

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