N = int(input())


def query(s):
    print("?", s, flush=True)
    return int(input())


# all a
a_count = query("a" * N)
ans = [None] * N
counter_query = 1

for c in "bcdefghijklmnopqrstuvwxyz":
    for i in range(N):
        if counter_query >= 2500:
            print("!", ("z" * N), flush=True)
            exit()
        if ans[i] is not None:
            continue
        lst = ["a"] * N
        lst[i] = c
        cnt = query("".join(lst))
        counter_query += 1
        if a_count < cnt:
            ans[i] = c
        elif a_count > cnt:
            ans[i] = "a"
print("!", "".join(ans), flush=True)