def dfs(v):
    while next_to[v] < K:
        u = next_to[v]
        next_to[v] += 1

        dfs(u)
        path.append(u)


K = 26

next_to = [0] * K
path = []
dfs(0)
path.reverse()


def c(x):
    return chr(x + ord('A'))


for i in range(K * K):
    a = path[i]
    b = path[(i+1) % len(path)]
    print(f'{c(a)}{c(b)}')