// Didn't succeed to do it with C so I did it with Node.js

const fs = require('node:fs');

const data = fs.readFileSync('./cypherpunk.txt', 'utf8');

// Don't do this in production please :)

console.log(
  data
    .split('\\n')
    .filter(Boolean)
    .map((line) => line[0] + line[line.length - 1])
    .toString() 
);