#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

int main()
{
    int n, k;
    cin >> n >> k;
    vector<int> a(n);
    for(int i=0; i<n; ++i)
        cin >> a[i];

    sort(a.begin(), a.end());
    int ret = 0;
    int sum = 0;
    for(int i=0; i<=n-k; ++i){
        sum += a[i];
        ret = max(ret, (a[n-1] * (i + 1) - sum) / (i + 1));
    }
    cout << ret << endl;

    return 0;
}