public class t4 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入一串数字:");
StringBuffer sb = new StringBuffer(scanner.next());
int index = sb.indexOf(".")>=0?sb.indexOf("."):sb.length();
//倒循环+,
for(int i=index-3;i>0;i-=3){
sb.insert(i,",");
}
System.out.println(sb.toString());
//正循环+,
StringBuffer sb2 = new StringBuffer(sb);
for(int i=index%3==0?+3:+2;i<=index;i+=3){
sb2.insert(i,",");
}
System.out.println(sb.toString());
}
}