#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int mxN=3e5;
int n, k;
ll a[mxN+1];
pair<ll, ll> dp[mxN+1][2];
pair<ll, ll> f(ll pen) {
dp[0][0]={0, 0};
dp[0][1]={-1e18, 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][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][0], dp[n][1]);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin>>n>>k;
for(int i=1; i<=n; i++)
cin>>a[i];
ll l=0, r=1e18;
ll fin=0;
while(l<=r) {
ll mid=(l+r)/2;
if(f(mid).second>=k) {
l=mid+1;
fin=mid;
} else {
r=mid-1;
}
}
cout<<f(fin).first+k*fin;
return 0;
}
