#include<bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pb push_back
#define ii pair<int, int>
#define sz(v) (int)v.size()
#define all(v) v.begin(), v.end()
using namespace std;
const int N = 3e5+5, mod = 1e9+7, inf = 1e18;
int n, k;
int a[N];
ii dp[N][2];
ii solve(int lmb) {
dp[0][0] = {0, 0};
dp[0][1] = {a[0]-lmb, 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]-lmb, 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() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> k;
for (int i=0; i<n; i++) cin >> a[i];
int lo = 0, hi = inf;
while (lo<hi) {
int mid = (lo+hi+1)/2;
if (solve(mid).se>=k) {
lo = mid;
} else {
hi = mid-1;
}
}
cout << solve(lo).fi+lo*k;
}
