package main

import (
	"io"
	"os"
)

func decode(path string) {
	fp, err := os.OpenFile(path, os.O_RDWR, 0644)
	if err != nil {
		panic(err)
	}
	defer fp.Close()
	b := make([]byte, 100)
	if _, err := io.ReadFull(fp, b); err != nil {
		panic(err)
	}
	for i := 0; i < len(b); i++ {
		b[i] ^= 0xFF
	}
	if n, err := fp.WriteAt(b, 0); n != len(b) || err != nil {
		panic(err)
	}
}

func main() {
	for _, path := range os.Args[1:] {
		decode(path)
	}
}