#!/usr/bin/env python3

def query(x):
    print(x, flush=True)
    r = input()
    if r == "ACCESS GRANTED": exit(0)
    return int(r[15:-4])

for l in range(1, 21):
    if query("A" * l) > 5: break

chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
chars += chars.lower()
s = ["A"] * l
for i in range(l):
    times = [query("".join(s[:i] + [c] + s[i + 1 :])) for c in chars]
    j = times.index(max(times))
    s[i] = chars[j]