#include <iostream>
#include <string>
#include <stdio.h>
#include <vector>
#include <map>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <iterator>
#include <stack>
#include <queue>
#include <set>
#include <climits>
using namespace std;
typedef long long ll;
typedef long double ld;
const ll MOD = 1e9 + 7;
const ll infmax = ~(1LL << 64 - 1);
const ll infmin = (1LL << 64 - 1);
pair<ll, ll> dp(vector<ll>& a, ll pen) {
ll n = a.size();
vector<vector<pair<ll, ll>>> dp(n, vector<pair<ll, ll>>(2));
dp[0][0] = {0, 0};
dp[0][1] = {a[0] - pen, 1};
for(ll 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].first + a[i] - pen, dp[i - 1][0].second + 1),
make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
}
return max(dp[n - 1][0], dp[n - 1][1]);
}
signed main() {
ll n, k; cin >> n >> k;
vector<ll> nums(n);
for(ll i = 0; i < n; i++) cin >> nums[i];
ll lo = 0, hi = 1e18;
while(lo < hi) {
ll mid = (lo + hi) / 2;
if(dp(nums, mid).second >= k) lo = mid + 1;
else hi = mid;
}
cout << dp(nums, max(lo - 1, 0LL)).first + max(lo - 1, 0LL) * k;
return 0;
}
