/*
* AUTHOR : Hydrolyzed~
* SCHOOL : RYW
* TASK : NOI19_feast
* ALGO :
* DATE :
* */
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#ifndef _DEBUG
// @==== Libary ====@ //
// @================@ //
#endif
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update> ;
// @=== Debugger ===@ //
#ifdef _DEBUG
#include "debug.hpp"
#else
#define dbg(...) 0
#endif
// @================@ //
using ll = long long;
const int MxN = 300030;
int n, k;
ll a[MxN];
pair<ll, int> dp[2][MxN];
// dp[0][i] = not eat i, (max sum, number of people)
// dp[1][i] = eat i, (max sum, number of people)
// make sure every people consume at least [mid]
// max sum contains remainder of [value of eating - mid * number of eating]
inline pair<ll, int> calc(ll mid) {
dp[0][1] = {0, 0};
dp[1][1] = {a[1] - mid, 1};
for(int i=2; i<=n; ++i) {
dp[0][i] = max(dp[0][i - 1], dp[1][i - 1]);
dp[1][i] = max(
make_pair(dp[0][i - 1].first - mid, dp[0][i - 1].second + 1),
dp[1][i - 1]
);
dp[1][i].first += a[i];
}
return max(dp[0][n], dp[1][n]);
}
inline void solution(){
cin >> n >> k;
for(int i=1; i<=n; ++i) {
cin >> a[i];
}
ll l = 0ll, r = 1e18 + 100;
while(l < r) {
ll mid = (l + r + 1ll) >> 1ll;
pair<ll, int> current_maximum_possible = calc(mid);
if(current_maximum_possible.second > k) {
l = mid;
}
else {
r = mid - 1ll;
}
}
pair<ll, int> answer = calc(l);
cout << answer.first + l * answer.second;
return ;
}
signed main(){
cin.tie(nullptr)->ios::sync_with_stdio(false);
int q = 1;
// cin >> q;
while(q--){
solution();
cout << "\n";
}
return 0;
}
// https://github.com/MasterIceZ/archive/tree/main/cpp-template
