Barnard17

I'm installing Gentoo when it says

>> activating mdev
>> making tmpfs for /newroot
>> attempting to mount CD:- /dev/sda
>> attempting to mount CD:- /dev/sdb
>> attempting to mount CD:- /dev/sdc
>> attempting to mount CD:- /dev/sdd
>> NO BOOTABLE MEDIUM FOUND. WAITING FOR NEW DEVICES ...
>> attempting to mount CD:- /dev/sda
>> attempting to mount CD:- /dev/sdb
>> attempting to mount CD:- /dev/sdc
>> attempting to mount CD:- /dev/sdd
>> attempting to mount CD:- /dev/sda
>> attempting to mount CD:- /dev/sdb
>> attempting to mount CD:- /dev/sdc
>> attempting to mount CD:- /dev/sdd
!! COULD NOT FIND CD TO BOOT, SOMETHING ELSE NEEDED!
>> determining root device ...
!! THE ROOT BLOCK DEVICE IS UNSPECIFIED OR NOT DETECTED.
Please specify a device to boot, or "shell" for a shell ...
boot () :: [here there be space to type]

What do I do?

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