我想问下这段代码打印结果好像没有同步，但找不出问题来

public class Main {
    public static void main(String[] args) {
        Counter t1 = new Counter();        
        Counter t2 = new Counter();        
        new Thread(() -> t1.add(100)).start();       
        new Thread(() -> t1.dec(100)).start();        
        
        new Thread(() -> t2.add(100)).start();        
        new Thread(() -> t2.dec(100)).start();        
        System.out.println("t1.count = " + t1.get());        
        System.out.println("t2.count = " + t2.get());   
    }
}
class Counter{
    private int count = 0;    
    public synchronized void add(int n){
        count += n;    
    }
    public synchronized void dec(int n){
        count -= n;    
    }
    public int get(){
        return count;    
    }
}