已知鸡和兔的总数量为n，总腿数为m。输入n和m，依次输出鸡的数目和兔的数目。如果无解，则输出No answer。(The total number of chickens and rabbits was known to be n, and the total leg number was m. Input n and m to output the number of chickens and the number of rabbits in turn. If there is no solu