Guess the Password

AtCoder

IDagc044_d

Time2000ms

Memory256MB

Difficulty—

**This is an interactive task.** You have to guess a secret password $S$. A password is a nonempty string whose length is at most $L$. The characters of a password can be lowercase and uppercase english letters (a, b, ... , z, A, B, ... , Z) and digits (0, 1, ... , 9). In order to guess the secret password $S$ you can ask queries. A query is made of a valid password $T$, the answer to such query is the edit distance between $S$ and $T$ (the operations considered for the edit distance are: removal, insertion, substitution). You can ask at most $Q$ queries. **Note**: For a definition of edit distance (with operations: removal, insertion, substitution), see [this wikipedia page](https://en.wikipedia.org/w/index.php?title=Levenshtein_distance&oldid=954598393). ## Constraints * $L = 128$ * $Q = 850$ * The secret password $S$ is chosen before the beginning of the interaction. ## Interaction To ask a query, print on Standard Output (with a newline at the end) ? $T$ The string $T$ must be a valid password. The answer $ans$ to each query shall be read from Standard Input in the form: $ans$ As soon as you have determined the hidden password $S$, you should print on Standard Output (with a newline at the end) ! $S$ and terminate your program. ## Judgement * **After each output, you must flush Standard Output.** Otherwise you may get `TLE`. * After you print (your guess of) the hidden password, the program must be terminated immediately. Otherwise, the behavior of the judge is undefined. * If the password you have determined is wrong, you will get `WA`. * If you ask a malformed query (for example because the string is not a valid password, or you forget to put `?`) or if your program crashes or if you ask more than $Q$ queries, the behavior of the judge is undefined (it does not necessarily give `WA`). [samples]

API Response (JSON)

{
  "problem": {
    "name": "Guess the Password",
    "description": {
      "content": "**This is an interactive task.** You have to guess a secret password $S$. A password is a nonempty string whose length is at most $L$. The characters of a password can be lowercase and uppercase engli",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "agc044_d"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "**This is an interactive task.**\nYou have to guess a secret password $S$. A password is a nonempty string whose length is at most $L$. The characters of a password can be lowercase and uppercase engli...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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