#include <bits/stdc++.h>

#define setIO(s) freopen(s".in","r",stdin)

#define P pair<int,int>

#define ll long long

#define maxn 100007

using namespace std;

int arr[maxn],l[maxn],r[maxn],mark[maxn];

priority_queue<P, vector<P>, greater<P> >q;

void del(int x) {

    l[r[x]]=l[x], r[l[x]]=r[x];

    mark[x]=1;

}

int main() {

    // setIO("input");

    int n,m,tmp=0,cnt=0;

    scanf("%d%d",&n,&m);

    for(int i=1;i<=n;++i) {

        int x;

        scanf("%d",&x);

        if(!x) continue;

        if(1ll*arr[tmp]*x>0) arr[tmp]+=x;

        else arr[++tmp]=x;

    }

    n=tmp;

    int sum=0;

    for(int i=1;i<=n;++i) {

        l[i]=i-1,r[i]=i+1;

        if(arr[i] > 0) ++cnt, sum+=arr[i];

        q.push(make_pair(abs(arr[i]), i));

    }

    while(cnt > m) {

        while(mark[q.top().second]) q.pop();

        int x=q.top().second;      q.pop();

        if((l[x]&&r[x]!=n+1) || arr[x] > 0) {

            sum-=abs(arr[x]);

            arr[x]+=arr[l[x]] + arr[r[x]];

            del(l[x]), del(r[x]);

            --cnt;

            q.push(make_pair(abs(arr[x]), x));

        }

        else del(x);

    }

    printf("%d\n",sum);

    return 0;

}