为什么我的线程用synchronized不能同步?


class Account{
private static int balance=50;
public int getBalance(){
return  balance;
}
public void withdraw(int amt){
balance=balance-amt;
}
}
public class fetchMoney implements Runnable {
private  Account count=new Account();
public static void main(String[]args){
fetchMoney  samin=new fetchMoney();
fetchMoney  wang=new  fetchMoney();
Thread one=new Thread(samin);
Thread two=new Thread(wang);
one.setName("samin");
two.setName("wang");
one.start();

two.start();
}
    public synchronized void run(){
    
     for(int x=0;x<5;x++){
System.err.println(Thread.currentThread().getName()+"-------- begin withdraw "+count.getBalance());    
            
     makeWithdraw(10);
            
System.err.println(Thread.currentThread().getName()+"-------- withdraw ok "+count.getBalance());    
     if(count.getBalance()<0){
     System.err.println("account is overdrawn~!");
     }
     }
    
    }
    private synchronized void  makeWithdraw(int amt){
     if(count.getBalance()>=amt){
     System.out.println(Thread.currentThread().getName()+" is going to withdraw "+count.getBalance());
    
    
     try{
     Thread.sleep(500);
     }catch(Exception e){
     e.printStackTrace();
     }
     count.withdraw(amt);
     System.out.println(Thread.currentThread().getName()+" is done withdraw "+count.getBalance());
    }
    else{
     System.out.println(Thread.currentThread().getName()+
     " sorry,not enough money "+count.getBalance());
    
    }
  }
}