///huynhocute123///
#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define piii pair<int,pair<int,int>>
#define pb push_back
#define FOR(i, a, b) for(int i = (a) , _b = (b); i <= _b; ++i)
#define REP(i, a, b) for(int i = (b) , _a = (a); i >= _a; --i)
#define ALL(v) v.begin(),v.end()
#define inp(name) if(fopen(name, "r")) freopen(name, "r", stdin);
#define out(name) if(fopen(name, "w")) freopen(name, "w", stdout);
//random_device rd;
//mt19937 rng(rd());
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
//#define int long long
const int MAX = 1e9+9;
const long long MAXLL = 1e18+9;
const double pi = 3.14159265358979323846;
const double rad = 3.14159265358979323846 /180;
bool minimize(int &u, int v){
if(v < u){
u = v;
return 1;
}
return 0;
}
bool maximize(int &u, int v){
if(v > u){
u = v;
return 1;
}
return 0;
}
bool maximizell(long long &u, long long v){
if(v > u){
u = v;
return 1;
}
return 0;
}
bool minimizell(long long &u, long long v){
if(v < u){
u = v;
return 1;
}
return 0;
}
const int mod = 1e9 + 7;
inline int fastPow(int a, int n){
if(n == 0) return 1;
int t = fastPow(a, n >> 1);
t = 1ll * t * t % mod;
if(n & 1) t = 1ll * t * a % mod;
return t;
}
const int maxN =232 ;
struct Alien_Trick{
vector<vector<pair<long long ,long long>>>dp;
vector<long long> a;
int n;
pair<long long , long long> SOL(long long lamba){
dp[1][0] = {0 , 0};
dp[1][1] = {a[1] - lamba, 1};
FOR(i, 2, n){
dp[i][0] = max(dp[i - 1][1] , dp[i - 1][0]);
dp[i][1] = max( make_pair(dp[i - 1][0].first + a[i] - lamba, 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] , dp[n][0]);
}
void init(){
int k;
cin >> n >> k;
a.assign(n + 2, 0);
dp.assign(n + 2 , vector<pair<long long ,long long>>() );
FOR(i, 1, n)dp[i].assign(4, pair<long long, long long >());
FOR(i, 1 , n)cin >> a[i];
long long l = 0 , r= 1e18 ,ans = -1;
while(l <= r){
long long mid = (l + r)/2;
pair<long long , long long> hih = SOL(mid);
if(hih.second >= k){
ans = mid;
l = mid + 1;
}else r = mid - 1;
}
pair<long long , long long> hih = SOL(ans);
cout << hih.first + ans * k;
}
};
Alien_Trick X;
inline void solve(){
X.init();
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
#define NAME "task"
if(fopen(NAME".inp", "r")){
freopen(NAME".inp", "r" ,stdin);
// freopen(NAME".out", "w" ,stdout);
}
int tc = 1;
// cin >> tc;
while( tc-- )solve();
cerr << '\n' << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << " s\n" ;
}
