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 # Projet3_first_pull_request
 
+Welcome to project 3! 
+This program allows to determine if a number is prime otherwise its prime 
+dividers are calculated.
+The numbers to be considered shall be in an file (*.txt) then the programme
+can be called with this sintax:
+
+./fact [-N number_of_threads] input_file.txt output_file.txt
+
+Whether the number of threads is not defined, the default number of threads is 2.
+The programme performance could not increase with a too high number of threads 
+because, above all, it will depend on the machine architecture (e.g. number of cores).
+The maximum number of threads allowed by the programme is 20, nevertheless 
+the programme "fact" can be updated by changing the constant MAX_NO_THREADS 
+(#define MAX_NO_THREADS 20).
+