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.util.*;
import java.io.*;

public class a2oj {

    static FastReader sc;
    static PrintWriter out;
    static int mod = 1000000007;

    public static void main(String[] args) throws IOException {
        if (System.getProperty("ONLINE_JUDGE") == null) {
            File f1 = new File("input.txt");
            File f2 = new File("output.txt");
            Reader r = new FileReader(f1);
            sc = new FastReader(r);
            out = new PrintWriter(f2);
            double prev = System.currentTimeMillis();
            solve();
            out.println("\n\nExecuted in : " + ((System.currentTimeMillis() - prev) / 1e3) + " sec");
        } else {
            sc = new FastReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            solve();
        }
        out.flush();
        out.close();
    }

    static void solve() {
        // int t = sc.nextInt();
        // StringBuilder ans = new StringBuilder("");
        // while (t-- > 0) {

        // }
        // out.println(ans);
        String s = sc.next();
        s = '0' + s;
        int n = s.length();
        int[] a = new int[n];
        int[] b = new int[n];
        a[0] = 0;
        b[0] = 0;

        for (int i = 1; i < n; i++) {

            if (s.charAt(i) == 'a') {
                a[i] = a[i - 1] + 1;
                b[i] = b[i - 1];

            }

            else {
                b[i] = b[i - 1] + 1;
                a[i] = a[i - 1];

            }

        }

        if (a[n - 1] == n - 1 || a[n - 1] == 0) {
            out.println(n - 1);

        } else {

            int max = 0;

            for (int i = 1; i <= n - 1; i++) {
                for (int j = n - 1; j >= i; j--) {
                    int temp = a[i - 1] + b[j] - b[i - 1] + a[n - 1] - a[j];
                    // out.println(temp) ;
                    if (temp > max)
                        max = temp;
                }
            }
            out.println(max);
        }
    }

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

    public static int digitsCount(long x) {
        return (int) Math.floor(Math.log10(x)) + 1;
    }

    public static boolean isPowerTwo(long n) {
        return (n & n - 1) == 0;
    }

    static void sieve(boolean[] prime, int n) { // Sieve Of Eratosthenes
        for (int i = 1; i <= n; i++) {
            prime[i] = true;
        }
        for (int i = 2; i * i <= n; i++) {
            if (prime[i]) {
                for (int j = 2; i * j <= n; j++) {
                    prime[i * j] = false;
                }
            }
        }
    }

    static void fillGraph(ArrayList<ArrayList<Integer>> adj) {
        int n = sc.nextInt(), m = sc.nextInt();
        for (int i = 0; i < n + 1; i++) {
            adj.add(new ArrayList<Integer>());
        }
        for (int i = 1; i <= m; i++) {
            int x = sc.nextInt(), y = sc.nextInt();
            adj.get(x).add(y);
            adj.get(y).add(x);
        }
    }

    static void dfs(ArrayList<ArrayList<Integer>> adj, boolean[] visited, int v) {
        visited[v] = true;
        out.print(v + " ");
        for (Integer i : adj.get(v)) {
            if (!visited[i])
                dfs(adj, visited, i);
        }
    }

    static void bfs(ArrayList<ArrayList<Integer>> adj, int V, int s) {
        boolean[] visited = new boolean[V];
        Queue<Integer> q = new LinkedList<>();
        visited[s] = true;
        q.add(s);
        while (!q.isEmpty()) {
            s = q.poll();
            out.print(s + " ");
            for (Integer i : adj.get(s)) {
                if (!visited[i]) {
                    visited[i] = true;
                    q.add(i);
                }
            }
        }
    }

    int fib(int n) { // n-th Fibonacci Number
        int a = 0, b = 1, c, i;
        if (n == 0)
            return a;
        for (i = 2; i <= n; i++) {
            c = a + b;
            a = b;
            b = c;
        }
        return b;
    }

    static long nCr(int n, int r) { // Combinations
        if (n < r)
            return 0;
        if (r > n - r) { // because nCr(n, r) == nCr(n, n - r)
            r = n - r;
        }
        long ans = 1L;
        for (int i = 0; i < r; i++) {
            ans *= (n - i);
            ans /= (i + 1);
        }
        return ans;
    }

    static long catalan(int n) { // n-th Catalan Number
        long c = nCr(2 * n, n);
        return c / (n + 1);
    }

    static class Pair implements Comparable<Pair> { // Pair Class
        long x;
        long y;

        public Pair(int x, int y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (!(o instanceof Pair)) {
                return false;
            }

            Pair pair = (Pair) o;

            if (x != pair.x) {
                return false;
            }
            if (y != pair.y) {
                return false;
            }

            return true;
        }

        @Override
        public int hashCode() {
            long result = x;
            result = 31 * result + y;
            return (int) result;
        }

        @Override
        public int compareTo(Pair o) {
            return (int) (this.x - o.x);
        }
    }

    static class Trip { // Triplet Class
        long x;
        long y;
        long z;

        Trip(long x, long y, long z) {
            this.x = x;
            this.y = y;
            this.z = z;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (!(o instanceof Trip)) {
                return false;
            }

            Trip trip = (Trip) o;

            if (x != trip.x) {
                return false;
            }
            if (y != trip.y) {
                return false;
            }
            if (z != trip.z) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            long result = 62 * x + 31 * y + z;
            return (int) result;
        }
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader(Reader r) {
            br = new BufferedReader(r);
        }

        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;
        }
    }
}