//ALL HAIL MEGATRON

using namespace std;

#include<bits/stdc++.h>

#define wl(n) while(n--)
#define fl(i,a,b) for(i=a; i<b; i++)
#define rev(i,a,b) for(i=a; i>=b; i--)
#define scan(n) scanf("%d", &n)
#define scans(s) scanf("%s", s)
#define scanc(c) scanf("%c", &c)
#define scanp(f) scanf("%f", &f)
#define scanll(l) scanf("%lld", &l)
#define scanllu(u) scanf("%llu", &u)
#define print(n) printf("%d\n", n)
#define prints(s) printf("%s\n", s)
#define printc(c) printf("%c\n", c)
#define printp(f) printf("%f\n", f)
#define printll(l) printf("%lld\n", l)
#define printllu(u) printf("%llu\n", u)
#define nline printf("\n")
#define mclr(strn) strn.clear()
#define ignr cin.ignore()
#define MOD 1000000007
#define ll long long int
#define u64 unsigned long long int
#define PB push_back

#define inf 1000000000000005

ll dp[10004][2002],n,k,c[10005];

ll foo(ll ind, ll cur)
{
	if(ind>=n && cur<=0)
		return 0;
	if(ind>=n && cur>0)
		return inf;
	if(cur>k)
		return inf;

	ll x = cur+k+1;

	ll& res = dp[ind][x];

	if(res!=-1)
		return res;

	res = min(c[ind] + foo(ind+1, -k), foo(ind+1, cur+1));

	return res;
}


int main()
{
	memset(dp,-1,sizeof(dp));
	scanll(n);scanll(k);
	ll i;
	fl(i,0,n)
		scanll(c[i]);

	printll(foo(0,0));

	return 0;
}