分别编写求两个数值（可以是浮点数，整数或字符）最大值，最小值和平均值的函数maximum, minimum, meanValue。另外，编写一个函数gcd求两个整数的最大公约数。-Respectively write to demand the two values ​ ​ (which can be floating-point, integer or character) maximum, minimum and average function of the maximum, minimum, meanValue. In addition, write a function gcd seeking the greatest common divisor of two integers.