package main

// 参考文章：

//     https://github.com/Unknwon/the-way-to-go_ZH_CN/blob/master/eBook/06.6.md

import (

    "fmt"

)

func main () {

     fmt.Printf("%d is even: is %t\n", , even()) // 16 is even is true

    fmt.Printf("%d is odd: is %t\n", , odd())

    // 17 is odd: is true

    fmt.Printf("%d is odd: is %t\n", , odd())

    // 18 is odd: is false

}

func even( nr int) bool {

    if nr ==  {

        return true

    }

    return odd(RevSign(nr) - )

}

func odd(nr int) bool {

    if nr ==  {

        return false

    }

    return even(RevSign(nr) - )

}

func RevSign(nr int) int {

    if nr <  {

        return -nr

    }

    return nr

}