n = int(input())
X = "abcdefghijklmnopqrstuvwxy"
ans = ["?" for _ in range(n)]
for x in X:
	cnt = 0
	z = ""
	for i in range(n):
		z += x
		print("?", z)
		m = int(input())
		if cnt != m:
			ans[i] = x
		cnt = m
for i in range(n):
	if ans[i] == "?":ans[i] = "z"
	
print("!", "".join(ans))