#pragma GCC optimize("O3,unroll-loops,fast-math")
#pragma GCC target("avx,avx2,bmi,bmi2,popcnt,lzcnt,tune=native")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
signed main(){
cin.tie(0)->sync_with_stdio(0);
int n,k; cin >> n >> k;
int a[n];
for(auto&x:a)cin>>x;
auto solve = [&](ll y){
pair<ll, ll> dp[n][2];
dp[0][0] = {0,0};
dp[0][1] = {a[0]-y, 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].first + a[i] - y, 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]);
};
ll l = 0, r = 1e18;
while(l < r){
ll m = (l+r+1)/2;
solve(m).second >= k ? l = m : r = m-1;
}
cout << solve(l).first + l*k << '\n';
return 0;
}
