#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int MAXN = 1e5 + 10;
int n, a, b[MAXN], cnt[MAXN];

inline int read() {
	int x = 0, f = 1;
	char ch = getchar();
	while (!isdigit(ch)) {
		if (ch == '-') f = -1;
		ch = getchar();
	}
	while (isdigit(ch)) {
		x = x * 10 + ch - '0';
		ch = getchar();
	}
	return x * f;
}

int main() {
	n = read(); a = read();
	for (int i = 1; i <= n; i++) b[i] = read();
	for (int i = 1; i <= n; i++) {
		cnt[i] = 3 - (b[(i % n + 1)] + b[i] + b[(i + n - 2) % n + 1]);
	}
	sort(cnt + 1, cnt + 1 + n);
	int ans = 0;
	for (int i = 1; i <= a; i++) ans += cnt[i];
	printf("%d\n", 3 * n - ans);
	return 0;
}