#include <bits/stdc++.h>
using namespace std;
using LL = long long int;
using ULL = unsigned long long int;
using LD = long double;
#define int LL
// #define double LD
template <typename T> using V = std::vector<T>;
using VI = V<int>;
using VVI = V<V<int>>;
using VVVI = V<V<V<int>>>;
using VD = V<double>;
using VVD = V<V<double>>;
#define PB push_back
#define RSV reserve
#define EB emplace_back
#define ALL(A) (A).begin(), (A).end()
#define SUM(A) std::accumulate(ALL(A), int(0))
#define SUMD(A) std::accumulate(ALL(A), double(0))
#define AVE(A) SUM(A)/(A).size()
#define AVED(A) SUMD(A)/(A).size()
#define MAX(A) *std::max_element(ALL(A))
#define MIN(A) *std::min_element(ALL(A))
template <typename T1, typename T2> using P = std::pair<T1, T2>;
template <typename T> using PI = P<int, T>;
using PII = PI<int>;
using PIS = PI<std::string>;
#define MP std::make_pair
#define F first
#define S second
#define FOR(I,A,B) for(int I=int(A); I<int(B); ++I)
#define FORR(I,A,B) for(int I=int(A); I>=int(B); --I)
#define REP(I,B) FOR(I,0,B)
constexpr int kMOD = 1e9+7;
const double kPI = std::acos(-1);
struct Read {
	auto operator()(void) {
		int d;
		std::cin >> d;
		return d;
	}
}read;
struct ReadReal {
	auto operator()(void) {
		double d;
		std::cin >> d;
		return d;
	}
}readR;
struct ReadString {
	auto operator()(void) {
		std::string s;
		std::cin >> s;
		return s;
	}
}readS;
struct ReadEof {
	bool operator()(void) {
		return std::cin.eof();
	}
}readEof;
struct Print {
	void operator()(void) {
		std::cout << " ";
	}
	void operator()(double lf) {
		std::cout << std::fixed << std::setprecision(16) << lf;
	}
	template <typename T> void operator()(T t) {
		std::cout << t;
	}
	template <typename T1, typename T2>
	void operator()(const std::pair<T1, T2> &pair, const std::string &sep = ":") {
		std::cout << pair.first << sep << pair.second;
	}
	template <typename T>
	void operator()(T begin, T end, const std::string &sep = " ") {
		if (begin == end) return;
		Print()(*begin);
		for(auto it = ++begin;  it != end; ++it) {
			Print()(sep);
			Print()(*it);
		}
	}
	template <typename T>
	void operator()(const std::vector<T> &v, const std::string &sep = " ") {
		Print()(v.cbegin(), v.cend(), sep);
	}
	template <typename T>
	void operator()(std::initializer_list<T> list, const std::string &sep = " ") {
		Print()(list.begin(), list.end(), sep);
	}
}print;
struct Println {
	void operator()(void) {
		std::cout << std::endl;
	}
	void operator()(double lf) {
		Print()(lf);
		Println()();
	}
	template <typename T> void operator()(T t) {
		Print()(t);
		Println()();
	}
	template <typename T1, typename T2>
	void operator()(const std::pair<T1, T2> &pair, const std::string &sep = ":") {
		Print()(pair, sep);
		Println()();
	}
	template <typename T>
	void operator()(T begin, T end, const std::string &sep = " ") {
		Print()(begin, end, sep);
		Println()();
		return;
	}
	template <typename T>
	void operator()(const std::vector<T> &v, const std::string &sep = " ") {
		Print()(v.cbegin(), v.cend(), sep);
		Println()();
	}
	template <typename T>
	void operator()(std::initializer_list<T> list, const std::string &sep = " ") {
		Print()(list.begin(), list.end(), sep);
		Println()();
	}
}println;

bool IsAllocatedTrackSize(const VI &v, int tracks, int track_size) {
	auto it = v.begin();
	auto corrent = *it;
	for (++it; it != v.end(); ++it) {
		if (corrent + *it <= track_size) {
			corrent += *it;
		} else {
			if (--tracks <= 0) return false;
			corrent = *it;
		}
	}
	return true;
}

auto BinarySearchTrackSize(const VI &v, int tracks) {
	auto begin = MAX(v);
	auto end = SUM(v);
	auto allocation_size = end;
	while(begin < end) {
		auto mid = (begin + end) / 2;
		if (IsAllocatedTrackSize(v, tracks, mid)) {
			allocation_size = mid;
			end = mid;
		} else {
			begin = mid + 1;
		}
	}
	return allocation_size;
}

signed main(void){
	cin.tie(0);
	ios::sync_with_stdio(false);

	auto case_size = read();
	auto tracks = read();
	VI cases;
	cases.RSV(case_size);
	REP(i, case_size) {
		cases.EB(read());
	}
	auto track_size = BinarySearchTrackSize(cases, tracks);
	println(track_size);
	return 0;
}



Measured memory_bytes: 3624