#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int maxn = 300005;
LL a[maxn], sum[maxn], dp[maxn][2], cnt[maxn][2];
int n, k;
pair<LL, LL> solve(LL penalty) {
memset(dp, 0, sizeof(dp));
memset(cnt, 0, sizeof(cnt));
dp[1][1] = a[1] - penalty;
cnt[1][1] = 1;
for (int i = 2; i <= n; i++) {
// dp[i][0]
if (dp[i - 1][0] >= dp[i - 1][1]) {
dp[i][0] = dp[i - 1][0];
cnt[i][0] = cnt[i - 1][0];
} else {
dp[i][0] = dp[i - 1][1];
cnt[i][0] = cnt[i - 1][1];
}
// dp[i][1]
if (dp[i - 1][0] + a[i] - penalty >= dp[i - 1][1]) {
dp[i][1] = dp[i - 1][0] + a[i] - penalty;
cnt[i][1] = cnt[i - 1][0] + 1;
} else {
dp[i][1] = dp[i - 1][1] + a[i];
cnt[i][1] = cnt[i - 1][1];
}
}
pair<LL, LL> ans;
if (dp[n][0] > dp[n][1]) {
ans = make_pair(dp[n][0], cnt[n][0]);
} else {
ans = make_pair(dp[n][1], cnt[n][1]);
}
return ans;
}
int main() {
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> a[i];
sum[i] = sum[i - 1] + a[i];
}
LL l = 0, r = int(1e18);
while (r - l > 1) {
LL mid = (l + r) / 2;
if (solve(mid).second >= k) {
l = mid;
} else {
r = mid;
}
}
cout << solve(l).first + l * k << '\n';
}
