using System;

class NumberStore
{
    int[] numbers = { 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023 };

    public ref int FindNumber(int target)
    {
        ref int returnVal = ref numbers[0];
        var ctr = numbers.Length - 1;
        while ((ctr > 0) && numbers[ctr] >= target)
        {
            returnVal = ref numbers[ctr];
            ctr--;
        }
        return ref returnVal;
    }

    public override string ToString() => string.Join(" ", numbers);
}