I need help with code for a small arduino project.

I will be using an Arduino Uno.
There are 4 buttons used as input, A,B,C,D. They are simple, 1-position buttons that go back to the initial position once you release them. Here is some technical info for the buttons, in case it’s needed http://www.tme.eu/gb/details/a327b07/push-button-switches/sci/a3-27b-07/
There is one electromagnetic lock used as output.
Programming rules should be like this:
If buttons A and B are pressed simultaneously for 1 second, the electromagnetic lock should open. Pressing buttons C and D at any time will not allow the lock to be opened in the next 3 seconds. So in order to open the lock you need to press A and B, and not press C or D for the previous 3 seconds and the next 1 second.
I only need the code and the pin notation for input and output.
If you are interested, let me know the cost and duration of delivering the code.

Thanks in advance,
Cristian