подскажите почему не проходит?
package com.javarush.task.task18.task1809;
/*
Реверс файла
*/
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws Exception{
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String file1 = reader.readLine();
String file2 = reader.readLine();
FileInputStream inputStream = new FileInputStream(file1);
FileOutputStream outputStream = new FileOutputStream(file2);
int x=inputStream.available();
byte[] buffer = new byte[inputStream.available()];
while (inputStream.available()>0){
inputStream.read(buffer);}
for (int i = x-1; i>0; i--){
outputStream.write(buffer[i]);
}
inputStream.close();
outputStream.close();
}
}