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 aabaaaa
 babbabaabbbbabwbvbhbbbaaabbabbbbbbbkabbbbabaaabbbbbbajabbaaabazbbbzbalbabbwbbaabbabacabdbabbbfaaabbb
 baaahbbbba
 ababavvvv
 abnxabbaab
 krflnzhter
 amaabbbbxaabbbabaabaabbaaabaaaaabibbabaabaaabaabcaaxabablbbbbmbbbaaaaaabbaabbbaaabaaaababaababbabbbb
 babbbaaaaaabbbaabaaaaaoaabababaababaaaaababaaaaaaabbbbbbaaapaabaaabaaababaaaabaaaabaaaaababaaaabaaab

5
 14
 42467327
 7
 7
 11
 0
 98718509
 813881762


import java.io.OutputStream;
import java.io.IOException;
import java.io.PrintWriter;
//import java.util.*;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStreamReader;
//import java.math.*;
 
/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
 
 
 
public class Main {
	static int k;
    public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        InputReader in = new InputReader();
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }
 
    static class TaskC {
    	
        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {   
        	String s=in.nextLine();
        	char[] a=s.toCharArray();
        	int n=s.length();
        	long[][] dp=new long[n+1][2];
        	dp[0][0]=1;
        	dp[0][1]=1;
        	int mod=1000000007;
        	for(int i=1;i<=n;i++) {
        		if(a[i-1]=='a') {
        			dp[i][0]=dp[i-1][0]+1;
        			dp[i][1]=dp[i-1][1];
        		}
        		else if(a[i-1]=='b') {
        			long x=dp[i-1][0]*dp[i-1][1];
        			if(x>=mod) {
        				x%=mod;
        			}
        			dp[i][1]=x;
        			dp[i][0]=1;
        		}
        		else {
        			dp[i][0]=dp[i-1][0];
        			dp[i][1]=dp[i-1][1];
        		}
        	//	out.println(dp[i][0]+" "+dp[i][1]);

        	}
        	long x=dp[n][0]*dp[n][1];
			if(x>=mod) {
				x%=mod;
			}
    		out.println(x-1);

        	
        	
        
        }

    }
    
    static class InputReader
    {
        BufferedReader br;
        StringTokenizer st;
 
        public InputReader()
        {
            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;
        }
    
    }
   
   
}