说明：  对于给定的整数n和m,用最少的f和g变换次数将n变换为m。由文件input.txt输入数据，结果（相应的变换序列）输出到文件output.txt。回溯的整数变换问题
(For a given integer n and m, with a minimum of f and g will transform the number of n transform for m. Input.txt input data from the document, the result (corresponding transformation sequence) output to the file output.txt. Back issues of the Integer Transform)