输入数字没有结果哪里错了

package for1;

import java.util.Scanner;

public class count {

public static void main(String[] args) {

Scanner input=new Scanner(System.in);

System.out.println("请输入数字：");

int num=input.nextInt();

int count=0;

do{

count++;

}

while(num/10!=0);

System.out.println("他是一个"+count+"位数");

}

}