N = int(input())

ans = []
for i in range(N):
	now = 0
	for c in range(25):
		u = chr(ord("a") + c)
		print("?","a" * c + u + "a" * (N - c - 1))
		d = int(input())
		
		if c == 0:
			 now = d
		else:
			if d == now:
				pass
			elif d < now:
				ans.append("a")
				break
			else:
				ans.append(u)
				break
	if len(ans) < i + 1:
		ans.append("z")
print("!","".join(ans))