package com.beijing.javase;
import java.util.Scanner;
public class AB {
static int b;
public static void main(String[] args) {
AB u =new AB();
Scanner s =new Scanner(System.in);
int a =s.nextInt(9999)+1;

    b =a;
    int c,d=0;
    
    for(int i =1;a>=3;i++) {
        c = a/3;
        d = c+a%3;
        u.M(d);
        a=d;
        
    }
    System.out.print(b);

}

public int M(int d) {
    b+=d;
    return d;
}

}

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 9999
at java.lang.String.substring(Unknown Source)
at java.util.Scanner.buildIntegerPatternString(Unknown Source)
at java.util.Scanner.integerPattern(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at com.beijing.javase.AB.main(AB.java:8)