把手机号中间4个换位****

import java.util.Scanner;

public class Phone {
	public static void main(String[] args) {
		Scanner sc=new Scanner (System.in);
		System.out.println("请输入一个手机号");
		String s=sc.next();
		
		String a= s.substring(3, 7);
		String d=s.replace(a, "****");
		System.out.println(d);
	}
	

}