能被15整除的最大整数

给定一个只包含数字 [0..9] 的字符串，求使用字符串中的某些字符，构造一个能够被15整除的最大整数。注意，字符串中的每个字符只能使用一次。

输入：程序从标准输入读入数据，每行数据由一串数字组成，长度为1到1000。

输出：针对每一行输入，输出一个结果，每个结果占一行。如果无法构造出能够被15整除的整数，请输出impossible。-The largest integer divisible by 15 can be given only contain a number [0 .. 9] of the string, seeking to use some of the characters in the string to construct one can be the largest integer divisible by 15. Note that the string for each character can only be used once. Input: program read from standard input into the data, each row of data from a string of numbers, the length of 1 to 1000. Output: For each line of input, output a result, each result line. If you can not construct can be an integer divisible by 15, please output impossible.