text: document.body.innerText.trim().split('\n')
    .map(l => l.split('').map(n => +n))
    .flatMap((line, y, lines) =>
      line.filter((n, x) =>
        [lines[y][x - 1], lines[y][x + 1], lines[y - 1]?.[x], lines[y + 1]?.[x]]
          .filter(k => k !== undefined)
          .every(k => k > n),
      ),
    )
    .reduce((a, b) => a + b + 1, 0)
  