#include<bits/stdc++.h>
using namespace std;
#define int long long
int n , k;
const int INF = (long long)300000 * 1000000000;
const long double EPS = 1e-3;
const int N = 3 * 1e5 + 2;
vector<long double> a;
pair<long double ,int> dp[N][2];
bool check(long double lambda){
dp[0][1] = {-INF , 0}, 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][1].first+a[i] , dp[i-1][1].second) ,make_pair(dp[i-1][0].first + a[i] - lambda , dp[i-1][0].second + 1));
}
return max(dp[n][0] , dp[n][1]).second >= k;
}
long double solve(){
long double l = 0;
long double r = INF;
while(l + EPS < r){
long double m = (l +r) / 2;
if(check(m)){
l = m;
}
else{
r = m;
}
}
return l;
}
signed main(){
cin>>n >> k;
a.resize(n+1);
for(int i = 1 ; i <= n ;i++)cin>>a[i];
long double lambda = solve();
check(lambda);
long double res = (long long)round((k * lambda) + max(dp[n][1] , dp[n][0]).first);
cout << res;
}
