public class Test {
	public static void Main() {
		var text = "aaaaaaaaaa\"aaaaaaaaaaaaaaaaa\naaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\naaaaa\"aaaaaaaaaa\"aaaaaaaaaaaaa";
		var open = false;
		System.Text.StringBuilder newText = new();
		foreach (var character in text) {
			if (character == '"' || (open && character == '\n')) {
				open = !open;
				newText.Append(character);
			} else newText.Append(open ? 'b' : character);
		}
		System.Console.WriteLine(newText);
	}
}
 
//https://pt.stackoverflow.com/q/69376/101

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