class class1
    {
        class1()
        {
            MyDictionary cDictionary = new MyDictionary();

        }

  class MyDictionary
    {
        Dictionary<string, string> dict= new Dictionary<string, string>();
        public void Add(string key,string value){
            dict.Add(key, value);
        }
        public bool ContainsKey(string key)
        {
            return dict.ContainsKey(key);
        }

        public Dictionary<string, string> getDictionary()
        {
            return dict;
        }

        public isKeyExistsSetValue(string key,string value){
dict[key]=value;
}
 
    }
 
   public void   myMethod(){
     for(int i=0;i<5;i++){
      if(cDictionary.ContainsKey){
           isKeyExistsSetValue(i , i+1);
}else{
cDictionary.Add(i,i+1);
}
}
   }

}