#include <fstream>
#define max(a,b) a > b ? a : b
using namespace std;
ifstream fin("transport.in");
ofstream fout("transport.out");
int n,k,s[16000],suma,maximao = -1,raspuns = 0;

void citire()
{
    fin>>n>>k;
    int i;
    for(i = 1; i <= n; ++i)
        {
            fin>>s[i];
            suma += s[i];
            maximao = max(maximao, s[i]);
        }
}



int main()
{  citire();
   raspuns = suma / k;
   if(maximao > raspuns)
        raspuns = maximao + 2;
   fout<<raspuns;
   return 0;
}