using System;
using System.Collections.Generic;
using System.Linq;

public class Test
{
	public class GrandParent{
		public List<Parent> parentList{ get; set; }
		public string name{ get; set; }
		public GrandParent(string name){
			this.name = name;
			this.parentList = new List<Parent>();
		}
	}
	public class Parent{
		public List<Child> childList{ get; set;}
		public string name{ get; set; }
		public Parent(string name){
			this.name = name;
			this.childList = new List<Child>();
		}
	}
	public class Child{
		public string city{ get; set;}
		public Child(string city){
			this.city = city;
		}
	}
	public static void Main()
	{
		Child c1 = new Child("ABC"), c2 = new Child("123"), c3 = new Child("tmp");
		Parent p1 = new Parent("p1"), p2 = new Parent("p2"), p3 = new Parent("p3");
		GrandParent g1 = new GrandParent("g1"), g2 = new GrandParent("g2"), g3 = new GrandParent("g3");
		
		p1.childList.Add(c1); p1.childList.Add(c2); 
		p2.childList.Add(c2); 
		p3.childList.Add(c3);
		
		g1.parentList.Add(p1); g1.parentList.Add(p2); g1.parentList.Add(p3);
		g2.parentList.Add(p2);
		g3.parentList.Add(p3);
		
		List<GrandParent> repo = new List<GrandParent>{g1, g2, g3};
		
		var filteredParents = from g in repo
                    		  from p in g.parentList
                    		  where p.childList.Any(c => c.city == "tmp")
                    		  select new Parent(p.name){
                    		 	 childList = p.childList.Where(c => c.city == "tmp").ToList()
                    		  };
                    		 
     	var filteredGrandParents = from g in repo
     							   from p in g.parentList
     							   where filteredParents.Any(fp => fp.name == p.name)
     							   select new GrandParent(g.name){
     							   	   parentList = g.parentList.Where(pp => filteredParents.Any(fp => fp.name == pp.name)).ToList()
     							   };
                    		 
        foreach(var g in filteredGrandParents){
        	Console.WriteLine(g.name);
        	foreach(var p in g.parentList){
        		Console.WriteLine("\t" + p.name);
        		foreach(var c in p.childList){
        			Console.WriteLine("\t\t" + c.city);
        		}
        	}
        	Console.WriteLine();
        }
	}
}