Encoding problem in a shiny app

[JojoSouza]

Any tips to solve encoding problem. I am not able to generate the up (↑) and down (↓) arrows in the code below. When running, the following warning message appears:

Warning messages:
1: unable to translate 'Maximize <U+2191>' to native encoding 
2: unable to translate 'Minimize <U+2193>' to native encoding

library(shiny)

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      fluidRow(
        column(
          width = 6,
          selectInput("maxmin", label = h5("Maximize or Minimize"),
                      choices = list("Maximize \u2191" = 1, "Minimize \u2193" = 2), selected = "")
        )
      )),
    
    mainPanel(
      
    ))
  
)

server <- function(input, output, session) {
  
}

shinyApp(ui = ui, server = server)