LAB#3 Pre-Work
                       DUE: 2/9/2023
      Submit a ZIP file of your work for TA to run you program
          WARNING: Independent work, NO COPYING ALLOWED !!!!		   

1. Copy the example program C4.1.c in the book as t.c
   Modify  N   to let A be an 8x8 matrix.
   Compile and run the program. Record the total output value ___________.

2. Define a global   int total = 0;
   Modify the func() code to let each thread add its row sum to total, as in

   //-------------------------------------
   int tmp = total;   // tmp = current total
   tmp += sum;        // update tmp locally 

   sleep(1);          // simulate interrupts, which may switch process/threads 

   total = tmp;       // write tmp to total
   //-------------------------------------
		      
   Modify main() to join with all threads; then print total value
		      
   Run the modified program. What's the total output value? _____________

3. Devise a way to make the modified code work CORRECTLY.
   HINT: read example program C4.3