多项式计算，完成功能：

(1)输入并建立多项式；

(2)输出多项式；

(3)两个多项式相加，建立并输出和多项式；

(4)两个多项式相减，建立并输出差多项式。-Polynomial terms, the completion of functions: (1) input and the establishment of polynomials　(2) the output polynomial　(3) the sum of two polynomials, and polynomials to create and output　(4) two polynomial subtraction, create and output differential polynomial.