#include <iostream>

#include <cstring>

#include <cstdio>

using namespace std;

#define INF 1000000000

#define REP(i,n) for(int i=0;i<(n);++i)

#define FOR(i,a,b) for(int i=(a);i<=(b);++i)

#define RFOR(i,a,b) for(int i=(a);i>=(b);--i)

int n, m;

int C[10005];

int mm[10005][105];

/*int dp(int now, int last) {

int& ret = mm[now][last];

if (ret != -1) return ret;

int idx = now + m - last;

if (idx >= n) return ret = 0;

ret = INF;

FOR(i,now+1,idx) {

int t = C[i] + dp(i, i - now);

ret = min(ret, t);

}

return ret;

}*/

int main() {

scanf("%d %d", &n, &m);

REP(i,n) scanf("%d", &C[i]);

//REP(i,10005) C[i] = 10000;

int res = INF;

memset(mm, -1, sizeof(mm));

FOR(i,1,m-1) mm[n - 1][i] = 0;

RFOR(i,n-2,0) {

FOR(j,1,m-1) {

if (i - j < 0) break;

int idx = i + m - j;

if (idx >= n) mm[i][j] = 0;

else {

mm[i][j] = INF;

FOR(k,i+1,idx) {

int t = C[k] + mm[k][k - i];

mm[i][j] = min(mm[i][j], t);

}

}

}

}

REP(i,m) {

FOR(j,i+1,m-1) {

int t = C[i] + C[j];

//t += dp(j, j - i);

t += mm[j][j - i];

res = min(res, t);

}

}

printf("%d\n", res);

return 0;

}