diff --git a/exercise3/wave_1d_parallel.c b/exercise3/wave_1d_parallel.c
index ef9847c..14eb4d0 100644
--- a/exercise3/wave_1d_parallel.c
+++ b/exercise3/wave_1d_parallel.c
@@ -124,7 +124,16 @@ void border_exchange(void) {
 // to root and assemble it in the root buffer
 void send_data_to_root() {
   // BEGIN: T7
-  ;
+  if (comm_rank != ROOT) {
+    MPI_Send(&U(0), n, MPI_DOUBLE, ROOT, 0, MPI_COMM_WORLD);
+  } else {
+    int offset = n;
+    for (int i = 1; i < comm_size; i++) {
+      int proc_n = N / comm_size + (i < N % comm_size);
+      MPI_Recv(&U(offset), proc_n, MPI_DOUBLE, i, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+      offset += proc_n;
+    }
+  }
   // END: T7
 }