Letter repetition - Dictionaries

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
//You will be given a single string, containing random ASCII character.Your task is to print every character, and how many times it has //been used in the string.
namespace Letter_Repetition
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<char, int> letters = new Dictionary<char, int>();
            string words = Console.ReadLine();

            for (int i = 0; i < words.Length; i++)
            {
                if (!letters.ContainsKey(words[i]))
                {
                    letters.Add(words[i], 0);
                }
                letters[words[i]]++;
            }
            foreach (KeyValuePair<char, int> letter in letters)
            {
                Console.WriteLine($"{letter.Key} -> {letter.Value}");
            }
        }
    }
}