using System;
using System.Linq;
using System.Collections.Generic;
 
class Program
{
    static void Main()
    {
        List<int> A = new List<int> { 12, 25, 32, 41, 56, 65, 78, 89, 90, 101 };
 
        var result = A.GroupBy(n => n % 10) // Группируем по последней цифре
                      .OrderBy(g => g.Key) // Сортируем по возрастанию ключа
                      .Select(g => $"{g.Key}:{g.Sum()}") // Формируем строки "D:S"
                      .ToList();
 
        Console.WriteLine(string.Join(", ", result));
    }
}

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