q = [1]
dp[1] = 1
g = -1
until q.empty?
    c = q.shift
    i = dp[c]
    if c == n
        g = i
    end
    d = c.bits
    [c + d, c - d].select { |v| RANGE.include?(v) }.each do |v|
        if  i + 1 < dp[v]
            q.push(v)
            dp[v] = i + 1
        end
    end
end
puts g