#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
int b[100005],c[100005];
int main(){
    int T = 1, kase = 0;
    //cin >> T;
    while (T--) {
        int n,a;
        cin>>n>>a;
        for(int i=1;i<=n;i++) scanf("%d",&b[i]);
        for(int i=1;i<=n;i++) c[i]=b[i]+b[i%n+1]+b[(i+n-2)%n+1];
        sort(c+1,c+n+1,greater<int>());
        int ans=0;
        for(int i=1;i<=a;i++) ans+=c[i];
        printf("%d\n",ans+(n-a)*3);
    }
    return 0;
}