which testcase give WA

Question(A-B Game): ABGAME Problem - CodeChef

My solution: CodeChef: Practical coding for everyone

Not getting which test case lead to WA for my solution

Try this A…BA…B Your output produces B (UtEyxE - Online IDE & Debugging Tool - Ideone.com) But Ans should be A. How:Second A moves one step instead of all three and then u can see you will be in a situation such that A will win.