diff --git a/Exercises/ex_1/master_worker/master-worker.c b/Exercises/ex_1/master_worker/master-worker.c
new file mode 100644
index 0000000..33d208e
--- /dev/null
+++ b/Exercises/ex_1/master_worker/master-worker.c
@@ -0,0 +1,68 @@
+# include <stdio.h>
+# include <stdlib.h>
+# include <mpi.h>
+
+void master(int);
+void worker(void);
+
+//------------------------------------------------------------------------------
+int main(int argc, char *argv[])   // master-worker
+{
+    int maxtask = 40;
+    int rank;
+
+    MPI_Init(&argc, &argv);
+
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+    if (rank == 0)
+	master(maxtask);
+    else
+	worker();
+    
+    MPI_Finalize();
+    return 0;
+}
+
+//------------------------------------------------------------------------------
+void master(const int maxtask)
+{
+    MPI_Status status;
+    int size, msg, task, dest;
+
+    MPI_Comm_size(MPI_COMM_WORLD, &size);
+
+    for (task = 1; task <= maxtask; task++)
+    {
+	MPI_Recv(&msg, 0, MPI_INT, MPI_ANY_SOURCE, 0, MPI_COMM_WORLD, &status);
+        MPI_Send(&task, 1, MPI_INT, status.MPI_SOURCE, 0, MPI_COMM_WORLD);
+    }
+
+    task = -1;
+    for (dest = 1; dest < size; dest++)
+    {
+	MPI_Recv(&msg, 0, MPI_INT, dest, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+	MPI_Send(&task, 1, MPI_INT, dest, 0, MPI_COMM_WORLD);
+    }
+}
+
+//------------------------------------------------------------------------------
+void worker(void)
+{
+    int rank, msg, task;
+
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+    do
+    {
+	MPI_Send(&msg, 0, MPI_INT, 0, 0, MPI_COMM_WORLD);
+	MPI_Recv(&task, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+
+	if (task >= 0)
+	{
+	    printf("rank %d: working on task %d\n", rank, task);
+	    system("sleep 1");
+	}
+    }
+    while (task >= 0);
+}