//晦暗的宇宙，我们找不到光，看不见尽头，但我们永远都不会被黑色打倒。——Quinn葵因
#include<bits/stdc++.h>
#define ll long long
#define N 500005

int c[N];
int b[N];
int n,a;
int ans = 0;

int main(){
    scanf("%d%d",&n,&a);
    for(int i = 1;i <= n;++i)scanf("%d",&b[i]),b[i] ^= 1;
    ans = 3 * n;
    for(int i = 1;i <= n;++i)c[i] = b[i] + b[(i) % n + 1] + b[(i + n - 2) % n + 1];
    std::sort(c + 1,c + n + 1);
    // for(int i = 1;i <= n;++i)std::cout<<c[i]<<" ";
    for(int i = 1;i <= a;++i)ans -= c[i];
    std::cout<<ans<<"\n";
    return 0;
}