package main

import (
    "io"
    "log"
    "os"
)

func main() {
    var (
        b []byte
        err error
    )

    if len(os.Args) > 1 && os.Args[1] != "-" {
        b, err = os.ReadFile(os.Args[1])
    } else {
        b, err = io.ReadAll(os.Stdin)
    }

    if err != nil {
        log.Fatalf("unable to read: %v", err)
    }

    println(string(b))
}