D

#include <bits/stdc++.h>

using namespace std;
#define ll long long

int main()
{
    ll int n, m;
    cin>>n>>m;

    vector<ll int> a(n);
    for(auto &e: a)
      cin>>e;

    ll int ans=1e18;
    ll int low=1, high=1e18;

    auto check = [&](ll int x)
    {
        ll int temp = 1;
        ll int sum = 0;

        for(auto e: a)
        {
            if(e > x)       return false;

            sum += e + (sum>0);

            if(sum > x)
            {
                sum = e;
                temp++;
            }
        }

        return (temp <= m);
    };

    while(low <= high)
    {
        ll int mid = (low + high)/2;

        if(check(mid))
            ans=mid, high=mid-1;
        else
            low=mid+1;
    }

    cout<<ans<<"\n";
}