4 digits

What is this?
Beside based on analytical thinking, this challenging game addresses almost all people from different occupations and students.
How to play?

User tries to guess the secret number which is 4-digit randomly generated by the computer.
Press the start button.
Write a 4-digit number into the textbox.
The program compares your and its own number.
The number of matching digits appears on the same line with your number and the right side of the game with "+" signal.
The number of the digits in wrong order appears next to "+ correct digits" with "-" signal.
Examining these information, find the magic number!