package main

import "fmt"
import "crypto/md5"
import "io"
import "log"
import "os"

func main() {
	if len(os.Args) < 2 {
		log.Fatalln("Usage my-md5 file")
	}
	f, err := os.Open(os.Args[1])
	if err != nil {
		log.Fatalln(err)
	}
	defer f.Close()

	h := md5.New()

	io.Copy(h, f)
	fmt.Printf("%x\n", h.Sum(nil))
}