ok = 0
ng = 1000

while((ng - ok) > 1):
    mid = (ok + ng) // 2
    print("?", mid, flush = True)
    res = input()
    if (res == "safe"):
        ok = mid
        continue
    else:
        print("?", mid + 1, flush = True)
        res2 = input()
        if (res2 == "out"):
            ng = mid
        else:
            ok = mid

print("!", ok, flush = True)