#include <fstream>
using namespace std;
ifstream fin("transport.in");
ofstream fout("transport.out");
int main(){
    long long i, NumarSaltele, NumarTransporturi, SumaTotalaSaltele, VolMaxSaltea, SumaInCamion = 0, VolMaxCamion = 0, v[16001];
    fin >> NumarSaltele >> NumarTransporturi;
    for (i = 1; i <= NumarSaltele; i++){
        fin >> v[i];
        SumaTotalaSaltele += v[i];
    }
    VolMaxSaltea = SumaTotalaSaltele/NumarTransporturi;
    for (i = 1; i <= NumarSaltele; i++) {
        if (SumaInCamion < VolMaxSaltea){
            SumaInCamion += v[i];
        } else {
            if (SumaInCamion > VolMaxCamion)
                VolMaxCamion = SumaInCamion;
            SumaInCamion = 0;
            i--;
        }
    }
    fout << VolMaxCamion;
    return 0;
};