#include <bits/stdc++.h>

#define forn(i, n) for(int i = 0; i < (int)n; ++i)
#define all(x) x.begin(), x.end()
#define el '\n'

using namespace std;

typedef vector<int> vi;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, a;
    cin >> n >> a;
    vi spc(n);
    vi ntbl(n);
    int ans = 0;
    forn(i, n){
        cin >> spc[i];
        if(spc[i] == 1){
            ans += 3;
            continue;
        }
        ntbl[(i - 1 + n) % n]++;
        ntbl[(i + 1) % n]++;
        ntbl[i]++;
    }
    sort(all(ntbl), greater<int>());
    int na = n - a;
    forn(i, na)ans += ntbl[i];
    cout << ans << el;
}