You wouldn't say, but I've lost 20% of my couch so far. Ouch. Get it?
Come on, that has to be the best couch joke you've seen sofa.
...
... Anyway, you look behind the Harold cushion, and you find a piece of paper.
It contains instructions to get to the next room:

"Read in the first_last_digit.txt file (no header)."
"Each line contains a random combination of letters and numbers."
"For each line, extract the first and the last number, and combine them into one."
"Then, sum up all these numbers; the sum can be used as the new hidden word." "For example, for the line 'kd1jd8d' the output should be 18 (1 and 8)."
"For the line 'di8e7du3kdh9' the output is 89 (8 and 9, ignoring 7 and 3)."
"For the line 'eur7e', the output is 77 (7 and 7, so twice)."

Where do you want to go?