C++ :

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
typedef long long ll;
const int maxn=100001;
ll n,m,tot,ma;
ll a[maxn];
//void work();
int main()
{
	//freopen("fruit.in","r",stdin);
	//freopen("fruit.out","w",stdout);
	cin>>n>>m;
	tot=0;ma=0;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		if(a[i]>ma) ma=a[i];
		tot+=a[i];
	}
	ll s=ma,t=tot+1;
	ll mid;
	while(s<t)
	{
		mid=(s+t)>>1;
		ll v=mid,gs=1;
		bool flag=0;
		for(int i=1;i<=n;i++)
		{
			if(a[i]<=v) v=v-a[i];
			else
			{
				v=mid-a[i];
				gs++;
			}
			if(gs>m)
			{
				s=mid+1;
				flag=true;
				break;
			}
		}
		if(!flag) t=mid;
	//	cout<<s<<' '<<t<<' '<<flag<<endl;
	}
	cout<<s<<endl;
//	while(1);
	return 0;
}