36.go

package main

import (
	"flag"
	"fmt"
	"log"
	"strconv"
)

func main() {
	isDecode := flag.Bool("d", false, "decode")
	flag.Parse()
	str := flag.Arg(0)
	if *isDecode {
		n, err := strconv.ParseUint(str, 36, 64)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Println(str, n)
	} else {
		n, err := strconv.ParseUint(str, 10, 64)
		if err != nil {
			log.Fatal(err)
		}
		out := strconv.FormatUint(n, 36)
		fmt.Println(str, out)
	}
}