server.R

library(shiny)
options(shiny.autoreload = TRUE)

shinyServer(function(input, output) {
   
  output$distPlot <- renderPlot({
    
    x    <- faithful[, 2] 
    bins <- seq(min(x), max(x), length.out = input$bins + 1)
    
    hist(x, breaks = bins, col = 'darkgray', border = 'white')
    
  })
  
})

ui.R

library(shiny)

fluidPage(
  
  titlePanel("Old Faithful Geyser Datass"),
  
  sidebarLayout(
    sidebarPanel(
       sliderInput("bins",
                   "Number of bins:",
                   min = 1,
                   max = 50,
                   value = 30)
    ),
    
    mainPanel(
       plotOutput("distPlot")
    )
  )
)