What is Wrong in this code......?

import java.util.*;
public class Main {

public static int func(int n, String str){
	if(n == 0) 
		return 1;
	int count = 0;
	count += func(n-1,str+"b");
	if(str.length() == 0 || str.charAt(str.length()-1) == 'b')
		count += func(n-1,str+"a");
	
	return count;
}
public static void main(String args[]) {
	Scanner sc = new Scanner(System.in);
	int t = sc.nextInt();
	for(int i = 0; i < t; i++){
		int n = sc.nextInt();
		System.out.println("#" + n + " : " + func(n,""));
	}
}

}