After creating a requested calculator Date and number of working days (for Russia) , similar to Date plus days, I thought that it would be nice to create a work day calculator similar to How many days are there between two dates?.
Note 1: Number of working days are counted without the final date. I.e. if you enter Monday and Tuesday, the number will be 1.
Note 2: As the working days shift to holiday are regulated by special decree of the government, which usually comes in late October, thecalculator will account only those dates that was in the reference book stated above