import java.io.RandomAccessFile;

public class sampleCode {

	public static void main(String[] args) {
		sampleCode inst = new sampleCode();
		inst.run();		
	}

	private void run() {
		try{
			String uid = System.getProperty("user.name");
			
			RandomAccessFile raf = new RandomAccessFile("users.txt", "rw");
			raf.skipBytes((int)raf.length()); 
			raf.writeBytes(uid + "\n");
			raf.close();
						
		}catch(Exception e){
			e.printStackTrace();
		}
		
	}
}
