Problem: One day Nikita found the string containing letters "a" and "b" only. 

Nikita thinks that string is beautiful if it can be cut into 3 strings (possibly empty) without changing the order of the letters, where the 1-st and the 3-rd one contain only letters "a" and the 2-nd contains only letters "b".

Nikita wants to make the string beautiful by removing some (possibly none) of its characters, but without changing their order. What is the maximum length of the string he can get?

Input

The first line contains a non-empty string of length not greater than 5 000 containing only lowercase English letters "a" and "b". 

Output

Print a single integer — the maximum possible size of beautiful string Nikita can get.

Examples

Input

abba


Output

4

Input

bab


Output

2

Note

It the first sample the string is already beautiful.

In the second sample he needs to delete one of "b" to make it beautiful.

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;

/*
TASK: CFB
LANG: JAVA
 */
public class CFB {
    static String input;
    static int n;
    static int[] dp1 , dp2 , dp3;
    public static void main(String[] args) throws IOException {
        FastScanner in = new FastScanner(System.in);
        input = in.next();
        n = input.length();
        dp1 = new int[n];
        dp2 = new int[n];
        dp3 = new int[n];
        if(input.charAt(n-1) == 'a'){
            dp1[n-1] = 1;
            dp2[n-1] = 0;
            dp3[n-1] = 1;
        }
        else{
            dp1[n-1] = 0;
            dp2[n-1] = 1;
            dp3[n-1] = 0;
        }
        for(int i = n-2; i >= 0; i--){
            dp3[i] = (input.charAt(i) == 'a' ? 1 : 0) + dp3[i+1];
            dp2[i] = (input.charAt(i) == 'b' ? 1 : 0) +  Math.max(dp3[i+1] ,dp2[i+1]);
            dp1[i] = (input.charAt(i) == 'a' ? 1 : 0) +  Math.max(dp2[i+1] ,dp1[i+1]);
        }
        System.out.println(Math.max(Math.max(dp1[0] , dp2[0]) , dp3[0]));
    }

    private static class FastScanner {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public FastScanner(InputStream stream) {
            this.stream = stream;
        }

        int read() {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) return -1;
            }
            return buf[curChar++];
        }

        boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        boolean isEndline(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

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

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

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

        public String next() {
            int c = read();
            while (isSpaceChar(c)) c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public String nextLine() {
            int c = read();
            while (isEndline(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndline(c));
            return res.toString();
        }
    }
}