#include <bits/stdc++.h>
using ll = long long;
using namespace std;
template<typename T> void umax(T &a, const T b) {a = max(a, b);}
template<typename T> void umin(T &a, const T b) {a = min(a, b);}
constexpr int MAXN = 3e5 + 1;
int N, K;
int A[MAXN];
pair<ll, ll> dp[MAXN][2];
pair<ll, ll> solve(ll mid) {
dp[0][0] = {0, 0};
dp[0][1] = {A[0] - mid, 1};
for (int i = 1; i < N; ++i) {
dp[i][0] = max(dp[i-1][0], dp[i-1][1]);
dp[i][1] = max(
make_pair(dp[i-1][0].first - mid + A[i], dp[i-1][0].second + 1),
make_pair(dp[i-1][1].first + A[i], dp[i-1][1].second)
);
}
return max(dp[N-1][0], dp[N-1][1]);
}
int main() {
cin.tie(0)->sync_with_stdio(false);
cin >> N >> K;
for (int i = 0; i < N; ++i) cin >> A[i];
ll l = 0, r = 1e18;
while (l < r) {
ll mid = (l + r + 1) >> 1;
if (solve(mid).second >= K) l = mid;
else r = mid - 1;
}
cout << solve(l).first + K * l;
return 0;
}
