// #pragma GCC optimize("O3")
// #pragma GCC target("avx2")
#include <bits/stdc++.h>
#define ll long long
#define int ll
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
using namespace std;
const int inf = 1e18 + 9;
const int MAX = 2e5 + 5;
const int LOG = 20;
const int MOD = 998244353;
void solve(){
int n, k; cin >> n >> k;
int arr[n + 1];
for(int i = 1; i <= n; ++i){
cin >> arr[i];
}
auto get = [&](int pen){
array<int, 2> dp[n + 1][2];
dp[1][0] = {0, 0};
dp[1][1] = {arr[1] - pen, 1};
for(int i = 2; i <= n; ++i){
dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
dp[i][1] = max((array<int, 2>){dp[i - 1][1][0] + arr[i], dp[i - 1][1][1]},
(array<int, 2>){dp[i - 1][0][0] - pen + arr[i], dp[i - 1][0][1] + 1});
}
array<int, 2> mx = max(dp[n][0], dp[n][1]);
return mx;
};
int l = 0, r = 3e14 + 100;
while(l < r){
int mid = (l + r + 1) / 2;
auto mx = get(mid);
if(mx[1] >= k){
l = mid;
}
else{
r = mid - 1;
}
}
auto a = get(l);
cout << a[0] + k * l << '\n';
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while(t){
t--;
solve();
}
}
