Brackets

public string isValidBrackets(string inputString)
{
	int counter = 0;

	char[] charArray = inputString.ToCharArray();

	for (int i=0; i<charArray.length; i++)
	{
		if (charArray[0] != '(')
		{
			return "Invalid";
		}
		if (charArray[i] == charArray('('))
		{	
			counter++;
			if ((charArray.length - 1) == i) 
				return "Invalid";
		}
		if (charArray[i] == charArray(')'))
		{
			counter--;
			if (counter == 0 && ((charArray.length - 1) == i)) ? "Valid" : "Invalid";
		}
		else 
		{
			continue;
		}
	}
	return "Invalid";
}