package main

import "fmt"
import "io"
import "io/ioutil"
import "log"
import "os"
import "strings"

var err error
var reader io.Reader

func openFile(path *string) *os.File {
	f, err := os.Open(os.Args[1])
	if err != nil {
		log.Fatalln(err)
	}
	return f
}

func readMe(r *io.Reader) {
	if content, err := ioutil.ReadAll(*r); err != nil {
		log.Fatalln(err)
	} else {
		fmt.Printf("%s", content)
	}
}

func main() {
	if len(os.Args) <= 1 {
		var content string
		if _, err := fmt.Scanln(&content); err != nil {
			log.Fatalln(err)
		}
		reader = strings.NewReader(content)
	} else {
		readers := []io.Reader{}
		for i := 1; i < len(os.Args); i++ {
			f := openFile(&os.Args[i])
			defer f.Close()
			readers = append(readers, f)
		}
		reader = io.MultiReader(readers...)
	}
	readMe(&reader)
}