c - P R O G R A M I N G

Write a function that receives an integer, b, that represents a number of bytes. If 1 ≤ b ≤ 8, the function will return the largest positive value that an unsigned int of b bytes can represent. If b is not in the appropriate range, the function should return -1. The function declaration is long largest(int); Assume that this function will be executed on a 64-bit operating system. You can use the pow() function which returns a double with the value b^e when called with pow(b, e). Can somebody help?