text: /**
   * Difference
   * Read four integer values named A, B, C and D. Calculate and print the difference of product A and B by the product of C and D (A * B - C * D).
   * 
   * Input
   * The input file contains 4 integer values.
   * 
   * Output
   * Print DIFERENCA (DIFFERENCE in Portuguese) with all the capital letters, according to the following example, with a blank space before and after the equal signal.
   */
  
  var readline = require('readline')
  
  var interface = readline.createInterface({
    input: process.stdin,
    output: process.stdout
  })
  
  var A, B, C, D, result = Number()
  
  interface.question('Insira A: ', numA => {
    A = Number(numA)
    interface.question('Insira B: ', numB => {
      B = Number(numB)
      interface.question('Insira C: ', numC => {
        C = Number(numC)
        interface.question('Insira D: ', numD => {
          D = Number(numD)
          result = ((A*B) + (C*D))
          interface.write(`Product = ${result}`)
          interface.close()
        })
      })
    })
  })
  