#include <iostream>
#include <fstream>
using namespace std;

ifstream in ("transport.in");
ofstream out ("transport.out");

const int N = 100000;
int v[N], n, k;

bool incap (int c){
    int nrt = 0, cc = 0;
    for (int i = 0; i < n; i++)
    {
        if(v[i] > c){
            return false;
        }
        if(v[i] > cc)
        {
            nrt++;
            cc = 0;
        }
        cc -= v[i];
    }
    return (nrt <= k);
}

int main()
{
    in >> n >> k;
    for (int i = 0; i < n; i++)
    {
        in >> v[i] >> endl;
    }
    int r = 0, pas = 1 << 27;
    while (pas != 0)
    {
        if (!incap(r + pas))
        {
            r += pas;
            pas /= 2;
        }
    }
    out << r + 1;
    return 0;
}