#include<bits/stdc++.h>
using namespace std;
#ifdef ONPC
#include"debug.h"
#else
#define debug(...) 42
#endif
#define endl '\n'
#define ll long long
#define pii pair<int,int>
#define F first
#define S second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(),a.end()
#define int long long
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
const int mod = 1e9 + 7;
const int MAXN = 1e6 + 15;
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;
int a[MAXN], n, k;
pair<ll, int> dp[MAXN][2];
pii solve(ll lampda){
dp[0][1] = {-lampda, 1};
dp[0][0] = {0, 0};
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].F + a[i] - lampda, dp[i - 1][0].S + 1),
make_pair(dp[i - 1][1].F + a[i], dp[i - 1][1].S));
}
return max(dp[n][0], dp[n][1]);
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> k;
for (int i = 1; i <= n; i++){
cin >> a[i];
}
ll lo = 0, hi = 1e18;
while (hi - lo > 1){
ll mi = (lo + hi) >> 1;
if (solve(mi).second >= k){
lo = mi;
} else {
hi = mi;
}
}
cout << solve(lo).F + k * lo;
}
