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".
import com.sun.org.apache.xerces.internal.util.SynchronizedSymbolTable;

import java.awt.*;
import java.io.*;
import java.lang.reflect.Array;
import java.util.*;
import java.util.List;

public class Newbie {

    static InputReader sc = new InputReader(System.in);
    static PrintWriter out = new PrintWriter(System.out);

    public static void main(String[] args) {
        solver s = new solver();
        int t = 1;
        while (t > 0) {
            s.solve();
            t--;
        }
    }

    static class descend implements Comparator<pair> {
        public int compare(pair o1, pair o2) {
            if (o1.a != o2.a) {
                return (int) (o1.a - o2.a) * -1;
            } else {
                return (o1.b - o2.b);
            }
        }
    }

    static class InputReader {
        public BufferedReader br;
        public StringTokenizer token;

        public InputReader(InputStream stream) {
            br = new BufferedReader(new InputStreamReader(stream), 32768);
            token = null;
        }

        public String next() {
            while (token == null || !token.hasMoreTokens()) {
                try {
                    token = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return token.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }

    static class card {
        long a;
        int cnt;
        int i;

        public card(long a, int cnt, int i) {
            this.a = a;
            this.cnt = cnt;
            this.i = i;
        }
    }

    static class ascend implements Comparator<pair> {
        public int compare(pair o1, pair o2) {
            if (o1.a != o2.a)
                return (int) (o1.a - o2.a);
            else
                return (int) (o1.b - o2.b) * -1;
        }
    }

    static class extra {

        static boolean v[] = new boolean[100001];
        static List<Integer> l = new ArrayList<>();
        static int t;

        static void shuffle(long a[]) {
            List<Long> l = new ArrayList<>();
            for (int i = 0; i < a.length; i++)
                l.add(a[i]);
            Collections.shuffle(l);
            for (int i = 0; i < a.length; i++)
                a[i] = l.get(i);
        }

        static long gcd(long a, long b) {
            if (b == 0)
                return a;
            else
                return gcd(b, a % b);
        }

        static boolean valid(int i, int j, int r, int c) {
            if (i >= 0 && i < r && j >= 0 && j < c)
                return true;
            else
                return false;
        }

        static void seive() {
            for (int i = 2; i < 100001; i++) {
                if (!v[i]) {
                    t++;
                    l.add(i);
                    for (int j = 2 * i; j < 100001; j += i)
                        v[j] = true;
                }
            }
        }

        static int binary(int a[], int val, int n) {
            int mid = 0, l = 0, r = n - 1, ans = 0;
            while (l <= r) {
                mid = (l + r) >> 1;
                if (a[mid] == val) {
                    r = mid - 1;
                    ans = mid;
                } else if (a[mid] > val)
                    r = mid - 1;
                else {
                    l = mid + 1;
                    ans = l;
                }
            }
            return (ans);
        }

        static long fastexpo(int x, int y) {
            long res = 1;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                }
                y = y >> 1;
                x = x * x;
            }
            return res;
        }

        static long lfastexpo(int x, int y, int p) {
            long res = 1;
            x = x % p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res = (res * x) % p;
                }
                y = y >> 1;
                x = (x * x) % p;
            }
            return res;
        }
    }

    static class pair {
        long a;
        int b;

        public pair(long a, int n) {
            this.a = a;
            this.b = n;
        }
    }
    static long m=(long)1e9+7;
    static class solver {
        void solve() {
            extra e = new extra();
            char c[] = sc.next().toCharArray();
            int l = c.length;
            long a=0,b=0;
            for(int i=l-1;i>-1;i--)
            {
                if(c[i]=='b')
                    b++;
                else
                {
                    a=(a+b)%m;
                    b=(b*2)%m;
                }
            }
            System.out.println(a);
        }
    }
}