n = int(input())
S = ["a"] * n
for i in range(1, n + 1):
    mi = 1 << 30
    ma = -1
    ss = "z"
    for j in range(25):
        s = chr(97 + j)
        S[i - 1] = s
        print("?", "".join(S), flush=True)
        res = int(input())
        mi = min(mi, res)
        if res > ma:
            ma = max(ma, res)
            ss = s

    if mi == ma:
        ss = "z"
    S[i - 1] = ss

print("!", "".join(S))