using System;
using System.IO;
using System.Linq;

class Program
{
    static void Main()
    {
        string filePath = "input.txt";
        string[] words = File.ReadAllText(filePath).Split(' ');
        var wordCount = words.GroupBy(w => w.ToLower())
                             .ToDictionary(g => g.Key, g => g.Count());

        string outputPath = "output.txt";
        File.WriteAllLines(outputPath, wordCount.Select(kv => $"{kv.Key}: {kv.Value}"));
    }
}