给定程序MODI1.C中函数fun的功能是：计算s所指字符串中含有t所知字符串的数目，并作为函数值返回。

请改正函数fun中指定部位的错误，使它能得出正确的结果。

注意：不要改动main函数，不得增行或删行，也不得更改程序的结构！

-MODI1.C in a given program function is a function fun: Calculation s t know referred to a string containing the number of strings, and returned as function value. Please specify the correct function fun parts of the error, so that it can reach the right result. Note: Do not change the main function, not by lines or delete lines, nor change the structure of the program!