MPI_Send(messages.data(), size-1, MPI_INT, (rank+1)%size, 0, MPI_COMM_WORLD);

  for (int i = 0; i < size-1; i++) {
    int sender = (rank == 0 ? size-1 : rank-1);
    if (sender-i < 0) {
      real_sender = size - reverse_index;
      reverse_index++;
    } else {
      real_sender = (rank == 0 ? sender - i : sender - i);
    }
    MPI_Recv(messages_to_pass.data(), size-1, MPI_INT, sender, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
    received_messages[real_sender] = messages_to_pass[0];
    messages_to_pass.erase(messages_to_pass.begin());
    MPI_Send(messages_to_pass.data(), size-1-i, MPI_INT, (rank+1)%size, 0, MPI_COMM_WORLD);
  }
}