using System.Collections.Generic;
using System.Linq;
public static class SumOfK
{
    public static int? chooseBestSum(int t, int k, List<int> ls) {
          int? ans = null;
        System.Console.WriteLine(ls.Count);
        if(k != 0 && ls.Count == 0){
          return null;
        }
        for(int i = 0; i < ls.Count; i++){
          if(k == 0){
            return 0;
          }
          var ls2 = new List<int>(ls);
          ls2.RemoveAt(i);
          System.Console.WriteLine(ls2.Count);
          var sum = chooseBestSum(t-ls[i], k - 1, ls2);
          if(sum + ls[i] <= t){
            sum +=ls[i];
          }else{
            continue;
          }
          if(ans == null || sum > ans){
            ans = sum;
          }
        }
        return ans;
    }
}