using System;

using System.Collections.Generic;

//count char in string using dictionary<char,int>           

​

public class Program

{

    public static void Main()

    {

        string str="Occurence";

        string strUp=str.ToUpper();

        Dictionary<char,int> dict=new Dictionary<char,int>();

        foreach(char ch in strUp)

        {

            if(dict.ContainsKey(ch))

                dict[ch]=dict[ch]+1;

            else

                dict.Add(ch,1);

        }

        foreach(var item in dict.Keys)

        {

            Console.WriteLine(item+":"+dict[item]);

        }

        Console.WriteLine("Hello World");

    }

}