#include <cstdio>
#include <cstring>
#include <cctype>
#include <algorithm>
#include <iostream>
#include <queue>
typedef long long LL;
using namespace std;
inline int read() {
    int num = 0 ,f = 1; char c = getchar();
    while (!isdigit(c)) f = c == '-' ? -1 : f ,c = getchar();
    while (isdigit(c)) num = (num << 1) + (num << 3) + (c ^ 48) ,c = getchar();
    return num * f;
}
const int N = 1e5 + 5;
int n ,A ,v[N]; bool vis[N];
signed main() {
    n = read() ,A = read();
    for (int i = 1; i <= n; i++) v[i] = read();
    priority_queue <int> q;
    int res = 0;
    for (int i = 1; i <= n; i++) {
        int l = (i + n - 2) % n + 1 ,r = (i % n) + 1;
        int s = v[l] + v[i] + v[r];
        q.emplace(3 - s);
        res += s;
    }
    for (int i = 1; i <= n - A; i++)
        res += q.top() ,q.pop();
    printf("%d\n" ,res);
}