using System;
 
public class Test
{
	public static void Main()
	{
		string input = "\"THIS IS \"inner1\" THE MAIN \"inner2\" SENTENCE\"";
		// First remove the out quotes, we will manually change them at the end.
		string result = input.Substring(1, input.Length - 2);
		// Replace quotes that follow space with « and replace quotes that precede space with »
		result = result.Replace(" \"", " «").Replace("\" ", "» ");
		// Add the outer chevrons around the result.
		result = string.Format("«{0}»", result);
 
		Console.WriteLine(result);
	}
}

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