Course Schedule with Prerequisites

You are given a list of pairs representing course prerequisites. Each pair (a, b) states that course a must be taken before course b. Write a program to find whether you can finish all courses. If possible, return a list with the order of courses to take. If not, return 'Cannot complete courses'. Input: - The first line contains an integer n (number of courses). - The subsequent lines contain the prerequisites as pairs of integers (total n-1 pairs). Output: - A list of courses in the order they should be taken or 'Cannot complete courses'. Example: Input: 4 2 1 3 1 3 2 Output: [1, 2, 3, 4]