class Program
{
    static void Main(string[] args)
    {
        string[] coinMoney = Console.ReadLine().Split(' ');
        if (int.Parse(coinMoney[1])/100 < int.Parse(coinMoney[0]))
        {
            Console.WriteLine("can't exchange");
        }
        else
        {
            if(int.Parse(coinMoney[0]) < 5)
            {
                Console.WriteLine("no exchange");
            }else
            {
                Console.WriteLine(int.Parse(coinMoney[0]));
            }
        }
    }
}