哪里错了？

public class HelloWorld{

public static void main(String[] args){

int num = 999;

int count = 0;

if(num>=0 && num<=999999999){

   while( num!=0){

    count++;

    num/=10;

}

System.out.println("它是个"+count+"位的数");

}else{

ystem.out.println("输入错误");

}

}

}