add element not found exception

Contracts/Exceptions/ElementNotFoundException.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Contracts.Exceptions
+{
+	public class ElementNotFoundException : Exception
+	{
+		public ElementNotFoundException() : base("Element not founded.")
+		{
+		}
+
+		public ElementNotFoundException(string message) : base(message)
+		{
+		}
+
+		public ElementNotFoundException(string message, Exception inner) : base(message, inner)
+		{
+		}
+	}
+}