You are in a dark room, strapped to a chair but with your arms free. You are sitting in front of an old terminal, with the following displayed on it.
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______________________
| 20 guesses remain. |
| Enter code: ____ |
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As you look closer at the screen, you hear a man's voice.
"You have 20 guesses to get the numeric code correct. After every guess, the machine will display a certain amount of /'s and X's. A slash means you got a correct number but in the wrong place, an X means a correct number is in the right place. You get it right, I release you. You don't, and you will meet a most painful death. Good luck."