The input file format is the following
N ( n = number of variables, stored as integer)
A,3 (Next N lines are variable names represent by string + comma + domain of this variables)
B,3
C,3
M (this line represents the number of constraints, stored as integers)
A,B,1,1 (Next M lines represents constraints, this line means var A =1, var B =1 is not allowed )
Output assignments will be stored in a txt file