#include <stdio.h>
int main()
{
	int n, m;
	int store[3001];
	int min = 0;
	scanf("%d%d", &n, &m);
	for (int k = 1; k <= n; k++)
	{
		scanf("%d", &store[k]);
	}
	for (int ks = 1; ks <= m; ks++)
	{
		min += store[ks];
	}
	for (int i = 2; i <= (n - m); i++)
	{
		int sum=0;
		for (int kpi = i; kpi <= (i + m); kpi++)
		{
			sum += store[kpi];
		}
		if (sum <=min)
		{
			min = sum;
		}
	}
	printf("%d", min);
	return 0;
}

用了很多次循环