We have a string of letters 'a' and 'b'. We want to perform some operations on it. On each step we choose one of substrings "ab" in the string and replace it with the string "bba". If we have no "ab" as a substring, our job is done. Print the minimum number of steps we should perform to make our job done modulo 109 + 7.

The string "ab" appears as a substring if there is a letter 'b' right after the letter 'a' somewhere in the string.

Input

The first line contains the initial string consisting of letters 'a' and 'b' only with length from 1 to 106.

Output

Print the minimum number of steps modulo 109 + 7.

Examples

Input

ab


Output

1


Input

aab


Output

3

Note

The first example: "ab"  →  "bba".

The second example: "aab"  →  "abba"  →  "bbaba"  →  "bbbbaa".
/*
 * Remember a 6 cgpa student can know more than a 10 cgpa student.
 * Grades don't determine intelligence, they test obedience.
 * I Never Give Up.
 * I will become Candidate Master.
 * I will defeat Saurabh Anand.
 * Skills are Cheap,Passion is Priceless.
 * Obsession is necessary.
 * Author : Sameer Raj
 */

import java.lang.reflect.Array;
import java.text.CollationElementIterator;
import java.util.*;
import java.util.Map.Entry;
import java.io.*;
import java.lang.Math.*;
import java.math.BigInteger;

import static java.lang.Math.*;
import static java.lang.System.*;
import static java.util.Arrays.fill;
import static java.util.Arrays.spliterator;
public class ContestMain implements Runnable{
	private static Reader in=new Reader();
	private static StringBuilder ans=new StringBuilder();
	private static long MOD= (long) (1e9+7);
	private static final int N=(int) (2e5+7); // 2e5+7
	//	private static ArrayList<Integer> v[]=new ArrayList[N];
	private static boolean mark[]=new boolean[N];
	//	private static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	/*Not try to hack the sort function*/
	public static void sort(long arr[]){
		for(int i=arr.length-1;i>=2;i--){
			int x=new Random().nextInt(i-1);
			long temp=arr[x];
			arr[x]=arr[i];
			arr[i]=temp;
		}
		Arrays.sort(arr);
	}
	public static void sort(int arr[]){
		for(int i=arr.length-1;i>=2;i--){
			int x=new Random().nextInt(i-1);
			int temp=arr[x];
			arr[x]=arr[i];
			arr[i]=temp;
		}
		Arrays.sort(arr);
	}
	public static void sort(String arr[]){
		for(int i=arr.length-1;i>=2;i--){
			int x=new Random().nextInt(i-1);
			String temp=arr[x];
			arr[x]=arr[i];
			arr[i]=temp;
		}
		Arrays.sort(arr);
	}
	public static void sort(Pair arr[]){
		for(int i=arr.length-1;i>=2;i--){
			int x=new Random().nextInt(i-1);
			Pair temp=arr[x];
			arr[x]=arr[i];
			arr[i]=temp;
		}
		Arrays.sort(arr);
	}
	private static long gcd(long a, long b){
		if(b==0)return a;
		return gcd(b,a%b);
	}
	public static long lcm(long a,long b){
		return min(a,b)*(max(a,b)/gcd(a,b));
	}
	/*--------------------------------------------------------------------------------------------------------------*/
	/*Code lies here*/
	@Override
	public void run(){
	    String s=in.next();
	    long total=0,cnt=0;
	    for(int i=s.length()-1;i>=0;i--){
	    	if(s.charAt(i)=='b')cnt=add(cnt,1);
	    	else{
	    		total=add(total,cnt);
	    		cnt=mult(cnt,2);
			}
		}
	    pn(total);
	}
	public static void main(String[] args) throws IOException{
		new Thread(null,new ContestMain(),"Accepted",1<<26).start();
		/* 0_0 I am watching you 0_0 */
	}
	static class Pair<T> implements Comparable<Pair>{
		int l;
		int r;
		Pair(){
			l=0;
			r=0;
		}
		Pair(int k,int v){
			l=k;
			r=v;
		}
		@Override
		public int compareTo(Pair o){
			if(l!=o.l)return (int)(l-o.l);
			return (int)(r-o.r);
		}
	}
	/* BINARY SEARCH FUNCTIONS */
	public static int bsearch(int l,int r,int val,int ar[]){
		int mid;
		while(l+1!=r&&l<r){
			mid=(l+r)/2;
			if(ar[mid]<val)l=mid;
			else r=mid;
		}
		if(ar[l]==val)return l;
		else if(ar[r]==val)return r;
		else return -1;
	}
	public static int ceilSearch(int l,int r,int val,int ar[]){
		int mid;
		while(l+1!=r&&l<r){
			mid=(l+r)/2;
			if(ar[mid]<val)l=mid;
			else r=mid;
		}
		if(ar[l]>=val)return l;
		else if(ar[r]>=val)return r;
		else return -1;
	}
	public static int ceilSearch(int l,int r,long val,long ar[]){
		int mid;
		while(l+1!=r&&l<r){
			mid=(l+r)/2;
			if(ar[mid]<val)l=mid;
			else r=mid;
		}
		if(ar[l]>=val)return l;
		else if(ar[r]>=val)return r;
		else return -1;
	}
	public static int floorSearch(int l,int r,int val,int ar[]){
		int mid;
		while(l+1!=r&&l<r){
			mid=(l+r)/2;
			if(ar[mid]>val)r=mid;
			else l=mid;
		}
		if(ar[r]<=val)return r;
		else if(ar[l]<=val)return l;
		else return -1;
	}
	public static int floorSearch(int l,int r,long val,long ar[]){
		int mid;
		while(l+1!=r&&l<r){
			mid=(l+r)/2;
			if(ar[mid]>val)r=mid;
			else l=mid;
		}
		if(ar[r]<=val)return r;
		else if(ar[l]<=val)return l;
		else return -1;
	}
	/* MODULAR OPERATIONS */
	private static long mod(long a,long b){ //a%b
		return (b+a%b)%b;
	}
	private static long modInv(long a){
		return powmod(a,MOD-2);
	}
	private static long powmod(long x,long n){
		if(n==0||x==0)return 1;
		else if(n%2==0)return(powmod((x*x)%MOD,n/2));
		else return (x*(powmod((x*x)%MOD,(n-1)/2)))%MOD;
	}
	public static long mult(long a,long b){
		return mod(mod(a,MOD)*mod(b,MOD),MOD);
	}
	public static long add(long a,long b){
		return mod(mod(a,MOD)+mod(b,MOD),MOD);
	}
	public static long sub(long a,long b){
		return mod(mod(a,MOD)-mod(b,MOD),MOD);
	}
	/* MAX-MIN FUNCTIONS */
	public static long min(long a,long b){
		return Math.min(a, b);
	}
	public static int min(int a,int b){
		return Math.min(a, b);
	}
	public static long max(long a,long b){
		return Math.max(a, b);
	}
	public static int max(int a,int b){
		return Math.max(a, b);
	}
	public static long min(long ar[]){
		return Arrays.stream(ar).min().getAsLong();
	}
	public static int min(int ar[]){
		return Arrays.stream(ar).min().getAsInt();
	}
	public static long max(long ar[]){ return Arrays.stream(ar).max().getAsLong();}
	public static int max(int ar[]){ return Arrays.stream(ar).max().getAsInt(); }
	//Reader Class
	static class Reader{
		BufferedReader br;
		StringTokenizer st;
		public Reader(){br=new BufferedReader(new InputStreamReader(System.in));}
		String next(){
			while(st==null||!st.hasMoreElements()){
				try{st=new StringTokenizer(br.readLine());
				}catch(IOException e){e.printStackTrace();}
			}
			return st.nextToken();
		}
		int nextInt(){return Integer.parseInt(next());}
		long nextLong(){return Long.parseLong(next());}
		double nextDouble(){return Double.parseDouble(next());}
		String nextLine(){
			String str="";
			try{
				str=br.readLine();
			}catch(IOException e){
				e.printStackTrace();
			}
			return str;
		}
	}
	//Looping methods
	static void rep(char ar[],int start,int end){
		for(int i=start;i<end;i++)
			ar[i]=in.next().charAt(0);

	}
	static void rep(int ar[],int start,int end){
		for(int i=start;i<end;i++)
			ar[i]=in.nextInt();

	}
	static void rep(long ar[],int start,int end){
		for(int i=start;i<end;i++)
			ar[i]=in.nextLong();
	}
	static void rep(String ar[],int start,int end){
		for(int i=start;i<end;i++)
			ar[i]=in.next();
	}
	static void rep(int ar[][],int n,int m){
		for(int i=0;i<n;i++){
			for(int j=0;j<m;j++)
				ar[i][j]=in.nextInt();
		}
	}
	static void rep(long ar[][],int n,int m){
		for(int i=0;i<n;i++){
			for(int j=0;j<m;j++)
				ar[i][j]=in.nextLong();
		}
	}
	//Printer Methods
	static void pn(Object o){out.print(o);}
	static void pln(Object o){out.println(o);}
	static void pln(){out.println();}
	static void pf(String format,Object o){out.printf(format,o);}
	//Appenders
	static void app(Object o){ans.append(o);}
	static void appn(Object o){ans.append(o+"\n");}
}