#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vl vector<ll>
#define ff(aa, bb, cc) for(ll aa = bb; aa < cc; aa++)
#define pb push_back
#define all(aaa) aaa.begin(), aaa.end()
#define rall(aaa) aaa.rbegin(), aaa.rend()
#define pll pair<ll, ll>
#define fi first
#define se second
#define vb vector<bool>
#define ed "\n"
#define vs vector<string>
vl arr;
ll n;
pll solve(ll x){
vector<vector<pll>> dp(n, vector<pll>(2));
dp[0][0] = {0, 0};
dp[0][1] = {arr[0]-x, 1};
ff(i, 1, n){
dp[i][0] = max(dp[i-1][0], dp[i-1][1]);
dp[i][1] = max(pll(dp[i-1][0].fi+arr[i]-x, dp[i-1][0].se+1),
pll(dp[i-1][1].fi+arr[i], dp[i-1][1].se));
}
return max(dp[n-1][0], dp[n-1][1]);
}
int main(){
ll k;
cin >> n >> k;
arr = vl(n);
ff(i, 0, n){
cin >> arr[i];
}
ll l = 0, r = 1e18;
while(l < r){
ll mid = (l+r+1)/2;
if(solve(mid).se >= k){
l = mid;
}
else{
r = mid-1;
}
}
cout << solve(l).fi+l*k;
}
