Initalize the variable in 01-intro MPI data distribution example

01-intro/01-intro.tex

@@ -195,7 +195,7 @@ \section{MPI data distribution}
         MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
 
         // Define message
-        int number;
+        int number = 0;
         if (world_rank == 0) {
             // If we are rank 0, set number to -1 and send it to process 1
             number = -1;