//Implement a sorted list of cities // Example: // A // Arkhangelsk // Astrakhan // B // Belgorod // ...

To implement a sorted list of cities grouped by the first letter, you can use the following approach:

1. Sort the array of cities alphabetically.
2. Iterate through the sorted list and group cities by their first letter.
3. Display the letter and the corresponding cities.

Example in JavaScript:

const cities = ["Arkhangelsk", "Astrakhan", "Belgorod", "Bryansk", "Vladivostok"];

// Sort the cities
cities.sort((a, b) => a.localeCompare(b, 'ru'));

// Group by the first letter
const grouped = cities.reduce((acc, city) => {
  const firstLetter = city[0].toUpperCase();
  if (!acc[firstLetter]) {
    acc[firstLetter] = [];
  }
  acc[firstLetter].push(city);
  return acc;
}, {});

// Output the result
for (const letter of Object.keys(grouped).sort()) {
  console.log(letter);
  grouped[letter].forEach(city => console.log(city));
}

Output:

A
Arkhangelsk
Astrakhan
B
Belgorod
Bryansk
V
Vladivostok

This approach is easily scalable and supports any set of cities.