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.math.*;
    import java.util.*;    
          public class Main1
           {
            private InputStream is;
            private PrintWriter out;
            static int MOD = (int)(1e9+7);
            ArrayList<Integer>[] amp;
            public static void main(String[] args) throws Exception
            {
                new Thread(null, new Runnable()
                {
                public void run()
                {
                    try {
         } catch (Exception e)
                    {
                        System.out.println(e);
                    }
                }
            }, "1", 1 << 26).start();
                new Main1().soln();
            }
            char ch[][];
            static ArrayList<Integer>[] g;
            static ArrayList<Integer> ar[];
            static long ok[];    
        //    static char a[][];
            static int phi[]=new int[500005];
            void solve()
            {
                String s=ns();
                int max=0;
                int a=0;int b=0;
                for(int i=0;i<s.length();i++)
                {
                      if(s.charAt(i)=='a')a++;
                      else b++;
                }
                max=Math.max(a,b);
                int pre[]=new int[s.length()];
                if(s.charAt(0)=='a')
                    pre[0]=1;
                for(int i=1;i<s.length();i++)
                {
                    if(s.charAt(i)=='a')pre[i]++;
                    pre[i]+=pre[i-1];
                }
                int suf[]=new int[s.length()];
                if(s.charAt(s.length()-1)=='a')
                    suf[s.length()-1]=1;
                for(int i=s.length()-2;i>=0;i--)
                {
                    if(s.charAt(i)=='a')
                        suf[i]++;
                    suf[i]+=suf[i+1];
                }
                
                for(int i=0;i<s.length();i++)
                {
                    int count=0;
                    for(int j=i;j>=0;j--)
                    {
                        if(s.charAt(j)=='b')
                        {
                            count++;
                        }
                        int curr=count;
                        if(j-1>=0)
                            curr+=pre[j-1];
                        if(i+1<s.length())
                            curr+=suf[i+1];
                            max=Math.max(max,curr);
                        
                    }
                    //System.out.println(max);
                }
                out.println(max);
        
            }
            public static String Binary(long x)
            {
                String ans="";
                while(x>0)
                {
                    ans+=(x%2);
                    x/=2;
                }
                return new StringBuilder(ans).reverse().toString();
            }
            
            public static long find(int v,int start,int end,int l,int r)
            {
                if(r < start || end < l)
                {
                    return 0;
                }
                if(l <= start && end <= r)
                {
                    return (tre[v]);
                }
                int mid = (start + end) / 2;
                long p1 = find(2*v, start, mid, l, r);
                long p2 = find(2*v+1, mid+1, end, l, r);
                return p1+p2;          
            }
            static long tre[]=new long[4000005];
            public static void Update(int v,int tl,int tr,int index,long val)
            {
                if(tl==tr)
                {
                    tre[v]+=val;
                }
                else
                {
                    int mid=(tl+tr)/2;
                    if(tl <= index &&index <= mid)
                    {
                        Update(2*v,tl, mid, index, val);
                    }
                    else
                    {
                        Update(2*v+1,mid+1,tr, index, val);
                    }
                    tre[v]=((tre[2*v]+tre[2*v+1]));
                }
            }
            
                boolean isPrime(int x)
                {
                if(x==0||x==1)
                    return false;
                for(int i = 2;i*1L*i<=x;i++) if(x%i==0) return false;
                return true;
            }
            int  p ;
            long modInverse(long a, long mOD2){
                return  power(a, mOD2-2, mOD2);
            }
            long power(long x, long y, long m)
            {
            if (y == 0)
            return 1;
            long p = power(x, y/2, m) % m;
            p = (p * p) % m;
        
            return (y%2 == 0)? p : (x * p) % m;
            }
            public static long gcd(long a, long b){
                if(b==0) return a;
                return gcd(b,a%b);
            }
            class Pair1 implements Comparable<Pair1>{
                long a;
                long b;
                long c;
                Pair1(long x,long y,long z){
                this.a=x;
                this.b=y;
                this.c=z;
                }
                public int hashCode() {
                    return Objects.hash();
                }
                
                @Override
                public int compareTo(Pair1 arg0) {
                    return (int)(arg0.c-c);
                }    
            }
            long power(long x, long y, int mod){
                long ans = 1;
                while(y>0){
                    if(y%2==0){
                        x = (x*x)%mod;
                        y/=2;
                    }
                    else{
                        ans = (x*ans)%mod;
                        y--;
                    }
                }
                return ans;
            }
            void soln() {
                is = System.in;
                out = new PrintWriter(System.out);
                long s = System.currentTimeMillis();
                solve();
                out.flush();
            }
             private byte[] inbuf = new byte[1024];
            public int lenbuf = 0, ptrbuf = 0;
            private int readByte() {
                if (lenbuf == -1)
                    throw new InputMismatchException();
                if (ptrbuf >= lenbuf) {
                    ptrbuf = 0;
                    try {
                        lenbuf = is.read(inbuf);
                    } catch (IOException e) {
                        throw new InputMismatchException();
                    }
                    if (lenbuf <= 0)
                        return -1;
                }
                return inbuf[ptrbuf++];
            }
            private boolean isSpaceChar(int c) {
                return !(c >= 33 && c <= 126);
            }
            private int skip() {
                int b;
                while ((b = readByte()) != -1 && isSpaceChar(b))
                    ;
                return b;
            }
            private double nd() {
                return Double.parseDouble(ns());
            }
            private char nc() {
                return (char) skip();
            }
            private String ns() {
                int b = skip();
                StringBuilder sb = new StringBuilder();
                while (!(isSpaceChar(b))) {
                    sb.appendCodePoint(b);
                    b = readByte();
                }
                return sb.toString();
            }
            private char[] ns(int n) {
                char[] buf = new char[n];
                int b = skip(), p = 0;
                while (p < n && !(isSpaceChar(b))) {
                    buf[p++] = (char) b;
                    b = readByte();
                }
                return n == p ? buf : Arrays.copyOf(buf, p);
            }
            private int[][] nm(int n, int m) {
                int[][] map = new int[n][m];
                for (int i = 0; i < n; i++)
                {
                    for(int j=0;j<m;j++)
                        map[i][j]=ni();
                }
                return map;
            }
            private int[] na(int n) {
                int[] a = new int[n];
                for (int i = 0; i < n; i++)
                    a[i] = ni();
                return a;
            }
            private int ni() {
                int num = 0, b;
                boolean minus = false;
                while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
                    ;
                if (b == '-') {
                    minus = true;
                    b = readByte();
                }
                while (true) {
                    if (b >= '0' && b <= '9') {
                        num = num * 10 + (b - '0');
                    } else {
                        return minus ? -num : num;
                    }
                    b = readByte();
                }
            }
            private long nl() {
                long num = 0;
                int b;
                boolean minus = false;
                while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
                    ;
                if (b == '-') {
                    minus = true;
                    b = readByte();
                }
                while (true) {
                    if (b >= '0' && b <= '9') {
                        num = num * 10 + (b - '0');
                    } else {
                        return minus ? -num : num;
                    }
                    b = readByte();
                }
            }
            private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
            private void tr(Object... o) {
                if (!oj)
                    System.out.println(Arrays.deepToString(o));
            }
        }