Classes, properties, methods, ling begining, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class building
    {
        bool _isBuilt;
        
        public bool isBuilt
        {
            get{return(_isBuilt);}
            set{_isBuilt = value;}
        }
        
        int _floor;
        
        public int floor
        {
            get{return _floor;}
            set{_floor = value;}
        }

}
    
    public sealed class BuildingsDistrict
    {
        private List<string> m_buildings = new List<string>();
        public List<string> Buildings {get{return m_buildings;}}
        
        public BuildingsDistrict(){}
    }
    
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("Hello, world!");
            
            building House = new building();
            Console.WriteLine("isBuilt = {0}",House.isBuilt);
            House.isBuilt = true;
            Console.WriteLine("isBuilt = {0}",House.isBuilt);
            
            Console.WriteLine(House.floor);
            House.floor = 5;
            Console.WriteLine(House.floor);
            
            Func<int,int,int> Multy = (a,b)=>a*b;
                        
            Console.WriteLine(Multy(7,8));
            
            int[] arr = new int[]{0,1,2,3,4,5,6,7,8,9};
            
            var Nechet = arr.Where(a => a%2==1).ToArray();
            
            BuildingsDistrict bld = new BuildingsDistrict
            {
                Buildings={"empire","state","ostankino"}
            };
            
            List<int> intList = new List<int>(){1,2,3,4,5};
            intList.Add(10);
            intList.Add(50);
            foreach(int i in intList)
            {
                Console.WriteLine(i + " " + intList.IndexOf(i));
                
            }
            
            var table = new Dictionary<string, int>(){{"A",1},{"B",2},{"C",3}};

}
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,19 sec, absolute running time: 0,16 sec, cpu time: 0,14 sec, average memory usage: 14 Mb, average nr of threads: 3, absolute service time: 0,36 sec