#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ll long long
int main(){
    cin.tie(0)->sync_with_stdio(0);
    cout.tie(0);
    int N,K;
    cin>>N>>K;
    vector<int>A(N);
    rep(i,N) cin>>A.at(i);
    vector<ll>ruiseki(N);
    int cnt=0;
    rep(i,N){
        cnt+=A.at(i);
        ruiseki.at(i)=cnt;
    }
    ll ans=0;
    int siz=0;
    priority_queue<int>pq;
    for(int i=0;i<K-1;i++){
        pq.push(ruiseki.at(i));
        ans+=ruiseki.at(i);
        siz++;
    }
    if(K==1){
        ans=-100000000000;
        rep(i,N){
            ans=max(ans,ruiseki.at(i));
        }
        cout<<ans<<endl;
        return 0;
    }
    for(int i=K-1;i<N;i++){
        if(pq.top()>=ruiseki.at(i)){
            ans-=pq.top()-ruiseki.at(i);
            pq.pop();
            pq.push(ruiseki.at(i));
            siz=i;
        }
    }
    cout<<ruiseki.at(siz-1)*K-ans<<endl;
}