Brackets Check

using System;

class AreBracketsCorrect
{
  //Write a program to check if in a given expression the brackets are put correctly.
  //Example of correct expression: ((a+b)/5-d).
  //Example of incorrect expression: )(a+b)).

  static void Main()
  {
    Console.WriteLine("Please enter your expression for brackets check:");
    string expression = Console.ReadLine();

    int countOpeningBracket = 0,
        countClosingBracket = 0;
    bool isOpened = false;
    int position = 0;

    for (int i = 0; i < expression.Length; i++)
    {
      if (expression[i] == '(')
      {
        countOpeningBracket++;
        isOpened = true;
      }
      if (expression[i] == ')' && isOpened == true)//If there is an opened bracket we could count the closed one
      {
        countClosingBracket++;
      }
      else if (expression[i] == ')' && isOpened == false)//Otherwise we exit the cycle because we have found an error
      {
        countOpeningBracket = -1;
        countClosingBracket = -1;
        position = i;
        break;
      }
      if (countOpeningBracket == countClosingBracket) //After each iteration we check if we have closed all open brackets and if so isOpened becomes false
      {
        isOpened = false;
      }
    }

    //Print the results
    if (countOpeningBracket == -1 && countClosingBracket == -1)
    {
      Console.WriteLine("Brackets problem encountered! There is a closing bracket that hasn't been opened at position {0}!", position);
    }
    else if (countOpeningBracket == countClosingBracket)
    {
      Console.WriteLine("The brackets in your expression are put correctly!");
    }
    else if (countOpeningBracket > countClosingBracket)
    {
      Console.WriteLine("The number of opening brackets that are not closed is {0}!", countOpeningBracket - countClosingBracket);
    }
    else
    {
      Console.WriteLine("The number of closing brackets that don't have opening ones is {0}!", countClosingBracket - countOpeningBracket);
    }
  }
}