Как ввести и отобразить два файла, используя блестящий в R?

Question

Вот мой код:

library(shiny)

# Define UI for data upload app ----
ui <- fluidPage(

  # App title ----
  titlePanel("Uploading Files"),

  # Sidebar layout with input and output definitions ----
  sidebarLayout(

    # Sidebar panel for inputs ----
    sidebarPanel(

      # Input: Select a file ----
      fileInput("file1", "Count matrix File (.csv)",
                multiple = TRUE,
                accept = c("text/csv",
                         "text/comma-separated-values,text/plain",
                         ".csv")),
      fileInput("file2", "Manifest File (.csv)",
                multiple = TRUE,
                accept = c("text/csv",
                         "text/comma-separated-values,text/plain",
                         ".csv")),

      # Horizontal line ----
      tags$hr(),

      # Input: Checkbox if file has header ----
      checkboxInput("header", "Header", TRUE),

      # Horizontal line ----
      tags$hr(),

      # Input: Select number of rows to display ----
      radioButtons("disp", "Display",
                   choices = c(Head = "head",
                               All = "all"),
                   selected = "head")

    ),
    # Main panel for displaying outputs ----
    mainPanel(

      # Output: Data file ----
      tableOutput("contents")
    )
  )
)

# Define server logic to read selected file ----
server <- function(input, output) {

  output$contents <- renderTable({

    # input$file1 will be NULL initially. After the user selects
    # and uploads a file, head of that data file by default,
    # or all rows if selected, will be shown.
    req(input$file1)

    df <- read.csv(input$file1$datapath,
             header = input$header)

    if(input$disp == "head") {
      return(head(df))
    }
    else {
      return(df)
    }
  })
}
# Run the app ----
shinyApp(ui, server)

У меня вопрос, как отобразить заголовок обоих наборов входных данных?