#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define fastio ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
#define int ll
typedef pair<int, int> pii;
const int mod = 2147483647;
const int inf = 1e18;
const int N = 3e5 + 5;
int n;
int a[N];
pii lambda(int mid){
pii dp[n + 1][2];
dp[0][0] = make_pair(0, 0);
dp[0][1] = make_pair(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].fi + a[i] - mid, dp[i - 1][0].se + 1), make_pair(dp[i - 1][1].fi + a[i], dp[i - 1][1].se));
}
return max(dp[n - 1][0], dp[n - 1][1]);
}
signed main(){
fastio
int k; cin >> n >> k;
for(int i = 0; i < n; i++) cin >> a[i];
int left = 0, right = inf, kq;
while(left < right){
int mid = (left + right + 1) / 2;
pii ans = lambda(mid);
if(ans.se >= k) left = mid;
else right = mid - 1;
}
int ans = lambda(left).fi + left * k;
cout << ans;
return 0;
}
