`end_of_day3.tar.gz` is our `work` directory at the 
end of day3 (Wednesday). This is where we will start from Thursday.

You can extract it by:

   tar -xzvf end_of_day3.tar.gz

then go to the build directory, configure, build and execute:

   cd end_of_day3/build/
   cmake ../ -DGeant4_DIR=$G4INSTALL/lib64/cmake/Geant4
   make 
   ./yourmain