def f(src, dest, n): if n == 1: print(chr(65 + src), chr(65 + dest)) return else: f(src, 3 - src - dest, n - 1) print(chr(65 + src), chr(65 + dest)) f(3 - src - dest, dest, n - 1) # @TIME def solve(testcase): f(0, 2, II()) for testcase in range(1): solve(testcase)