帮忙看看这个程序哪里出错了？
数三退一的小程序。

public class Count3Quit2 {
public static void main(String[] args ) {
KidCircle kc = new KidCircle(500);
int countNum = 0;
Kid k = kc.first;
while(kc.count > 1 ) {
countNum ++;
if(countNum == 3) {
countNum = 0;
kc.delete(k);
}
k = k.right;
}

System.out.println(kc.first.id);

}
}

class Kid {
int id;
Kid left;
Kid right;
}
class KidCircle {
int count = 0;
Kid first, last;

KidCircle(int n) {
for(int i=0; i<n; i++) {
add();
}
}

void add() {
Kid k = new Kid();
k.id = count;
if(count <= 0) {
first = k;
last = k;
k.left = k;
k.right = k;

}
}

------解决方案--------------------
KidCircle没写delete方法