G = [[1] * 26 for _ in range(26)]

ans = []
for i in range(26):
	ans.append((i, i))
	ans.append((i, (i + 1) % 26))
	G[i][i] = 0
	G[i][(i + 1) % 26] = 0

now = 0
for _ in range(24 * 26):
	for i in range(26):
		if G[now][i] == 0:
			continue
		ans.append((now, i))
		G[now][i] = 0
		now = i
		break

for x in ans:
	print(chr(ord('A') + x[0]) + chr(ord('A') + x[1]))